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Video tags
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Russian
00:00:04
so the earring is our topic who knows no00:00:08
of course not if you're watching00:00:11
what is written00:00:13
that's exactly what is not true here too00:00:16
answers correctly who was at the 1st lecture00:00:19
where he told me the plan and like the most00:00:23
attentive of those who were accurate00:00:29
of course that's why I wrote here00:00:31
today look I will teach you to write00:00:33
request what is this as I said in00:00:37
relational databases00:00:38
two important things about this diagram when you00:00:41
you can create some objects in the database00:00:43
data and we talked a little about the project in00:00:46
last time, how's everything according to the signs?00:00:48
this is to sort and and the second actually00:00:54
in fact, even more important than the diagram00:00:56
is it select and why is it more important because00:01:00
most likely you will encounter00:01:02
completely different systems00:01:05
relational databases there with00:01:08
complex and so on and they all have00:01:11
the interface for you will be writing00:01:13
selecta00:01:14
if you ever become I don't know00:01:16
analytics by the manager there by anyone in00:01:21
eventually you will have some00:01:23
the data is somewhere, I know where, but more often00:01:26
in all you will address them as00:01:30
at least in selecta similar form therefore00:01:34
today I will tell you everything that00:01:36
I know about select and00:01:37
and teach and teach you really thinks00:01:40
a little bit more relational than you00:01:42
got used to it, that's actually the most important thing00:01:45
Today we will look at this whole course00:01:48
everything I know is most likely from designs00:01:49
selector I call you to this00:01:52
wonderful board so I'm not the only one here00:01:54
you wrote too00:01:56
and next time I will bring you problems 1000:02:01
I will distribute them in pairs of different problems and00:02:07
try writing something yourself00:02:09
straight guy we'll check it out00:02:11
and let’s look at it, but everyone calls it clear00:02:14
select and let's begin, I'm afraid to start writing00:02:19
I can't write, wait00:02:23
oh my god my pencil everything is so right here00:02:32
I'll start writing and now it's cool00:02:36
select00:02:39
school00:02:48
buy00:02:52
look, it’s easier to write in chalk, my handwriting00:02:58
Of course it’s special, it’s clear now00:03:03
look I do it like this, fire yeah00:03:13
this gives me a little shock00:03:20
the wonderfulness of us is such means00:03:21
let's try the telly with knowledge00:03:23
actually apply it practically00:03:25
all standard00:03:27
the words in the claim or are they written exactly in00:03:33
in this order today we are all of them00:03:35
We'll look at it and try to figure it out00:03:38
Let's start with the order let's say it00:03:45
I’ll write right away to write out the climate00:03:48
Of course it bothers me a little00:03:54
1 first thing to do with tie it carts00:03:58
Always00:03:59
about the second filters 3 coarse00:04:05
lay on you 4 having now unusual00:04:09
select and the fifth and sixth are executed00:04:13
condition00:04:14
or part of a buy order request, all of that is us00:04:16
let's leave now let's start from the top00:04:20
down they are from order and then about order00:04:22
I'll also tell you something00:04:24
your own select select actually00:04:26
very simple in the simplest form there will be00:04:31
just listing the fields of which you00:04:33
you want to choose let's say00:04:37
select, they can all be separated by commas00:04:43
not only names can be acceptable00:04:46
constants and let's say a moment00:04:54
may actually be an expression00:04:59
some yes, let's say one plus three with00:05:07
It’s clear that I just called it that00:05:10
you can write it like this00:05:16
look00:05:20
1 equals 1 + 300:05:24
some versions of the database already support it00:05:26
that is, roughly speaking, using c to call a00:05:28
through name equals00:05:30
and the expression can be in the gti village right in00:05:34
selecta expression00:05:35
write under select, yes and00:05:41
age up to this will be the expression one plus00:05:47
three everything's right look it's just me00:05:49
I say let’s say now watch this00:06:00
means no matter how many rows from here I would not return00:06:02
how quickly turned in the column under00:06:05
the name of the nickname will always be a letter, but00:06:09
so that is, if they return it, let’s say00:06:12
if you are here there is no verification00:06:14
I return all the lines from table a and00:06:17
I say that I will return00:06:18
then for some reason I’ll call everyone’s name and everyone00:06:22
I will say that they are all 4 year olds twice and00:06:26
then there’s another field, I understand, no I00:06:31
I don't do anything from the table and it's just me00:06:34
I return some data in table a00:06:37
there is already data, it’s obvious what’s there00:06:40
at least there is no I invented them00:06:45
before in the results I say that look I00:06:48
from the sign and I choose the name here on00:06:51
they care00:06:53
then I say that my results are00:06:55
if you have a nickname column00:06:57
which in fact will always be00:06:59
contain a or let's say look you can00:07:01
write like this like this blue00:07:04
and that is, I kind of just choose a nickname00:07:09
I’m adding a letter, but there I can even00:07:15
write something on request00:07:19
here I don’t know frome guru well00:07:33
Let's say there's some kind of VR to write there00:07:36
boom boom boom boom it doesn't matter00:07:39
there is a gti in the village itself only in the00:07:41
village gti can be under select that is00:07:44
you're actually practically practically00:07:46
can be built under any location00:07:49
select that is, it’s like this00:07:50
recursive dice select is a piece00:07:52
select00:07:54
this plus minus is understandable, most likely there00:08:03
he will only take the first entry before the claim00:08:05
one field but if you wrote it like that then you00:08:09
you can write here let's say 10 limit00:08:12
money here the choice is only a group or00:08:14
let's say you always return the filter00:08:15
but the entry in general is most likely there00:08:17
recording you later a little more about00:08:20
We'll talk about that a little further00:08:22
let's move forward with this, it's clear that it's simple00:08:24
select is you how you in you choose00:08:27
some speakers00:08:30
give me a name, yes, here, yes, that is, you00:08:49
you say that in fact I have00:08:50
there is a name there is no there is something else and00:08:53
let's say you want a group of people00:08:56
pull it out and you can do it right here00:08:59
define it right here in the title00:09:09
yes in this example in this example exactly00:09:14
then in this example you we will take them00:09:16
then to and menu we will add and make from00:09:19
his nickname there and from the bar and so on we00:09:24
add the letter a and call it nickname do00:09:28
it's actually possible and simple00:09:30
rename yes, that is, you can write00:09:32
here here name is there m200:09:37
yes it was cool if I own it00:09:45
I’ll just be here, it’s not brutal, it’s clear00:09:47
with this piece come on Igor or00:09:51
Lyokha00:09:53
here in this select and it’s no longer there, of course00:10:00
yes, look, you are forming a request in your00:10:12
the table contains data about how long you are here00:10:14
columns you request so many you will return00:10:16
you really need so much00:10:18
actually ask for exactly as much as you want00:10:20
need to, well, this is one plus 34 new type of edge00:10:32
yes, that is, age, well, the edge00:10:37
one is still the same will be simple00:10:41
another way to call it just syntax00:10:42
another one can be written like this and like this00:10:43
just write a little, look what00:10:46
It’s also important to write it simply like this00:10:49
you can usually find such a request00:10:51
select00:10:52
asterisk what does it mean00:10:56
let's somehow know this correctly00:10:59
throw away the ecology that is where00:11:03
yeah now it went further 3 points but00:11:08
if we do some kind of john here00:11:10
then boom boom boom boom boom00:11:13
then in fact it will be an asterisk00:11:15
mean all signs in general that00:11:17
got tied up network that is she00:11:20
include this sign whining about Jaina00:11:25
we'll talk a little later boom boom boom00:11:27
boom boom boom boom boom class still fire00:11:30
but select asterisk is considered anti00:11:33
pattern in database use00:11:35
why oh yes why long why is this00:11:38
maybe longer but a lot of extra stuff00:11:43
that's right Lyokha you should ask exactly00:11:44
what you need, as it were, and then you have it00:11:46
you get it faster, just not always00:11:48
faster than but then the likelihood is00:11:51
that you will get it faster than00:11:54
something that always gave up everything00:11:55
so you need to try in quantity00:11:59
lines ask for what you need and accordingly00:12:02
quantity yes but in the data ask for what00:12:06
necessary but that's it so what else is there in the village00:12:09
gti has a cool design something like00:12:14
simple ifa is called a case that is00:12:17
you can write like this in Kyiv00:12:20
write you say we are equal to Sergey D00:12:36
godmother wells00:12:45
but it’s no use but it’s too long to write just news00:12:49
yes m d ap00:12:55
well I see what it is00:12:59
the simplest option iv and that is, if you00:13:02
want to00:13:05
generate some column in00:13:08
depending on the values in this column00:13:10
Well, in Excel, everything was already written there, it’s given00:13:13
because it's theirs and there's something there00:13:16
tint red if there is less there00:13:19
20 paint green if more than a hundred00:13:22
it's the same design but actually00:13:26
in fact, with the help of the operator the case can00:13:28
do it simply00:13:29
the magic date may be right in it Sergei00:13:33
equal to Alexey event on his00:13:36
as well as mountains and nested cases00:13:39
may also be yes there v.n. and here00:13:43
again the case is pum-pu-rum-pu-pum in general00:13:45
completely all humidity is maintained00:13:49
that's practically all you need to know about00:13:53
select we still have everything up to the value up00:14:02
I'm the right one you can take and that's all00:14:08
this request so I'll try it now00:14:12
you can do it right here, you can take it00:14:13
delete00:14:19
so wait, not exactly like me00:14:25
wanted so so so so so now oh so00:14:38
I’ll take this and add it later, it’ll be shorter here00:14:49
so well so let's switch to a pencil00:14:53
hide the pencil and write here no VAT00:15:00
you know the status yes it will be from another one00:15:06
status column which is for earrings00:15:11
what is their status quo for you Igor here00:15:14
so just invaded from the bad and select00:15:19
it turned out bad that's cool because yes00:15:29
yes yes they should be one yes they should00:15:32
be the same type you're not really00:15:34
should actually enter these00:15:36
almost always under this on this00:15:38
here the parameters will find the most common of them00:15:40
like, well, it will fall if you start here00:15:44
someone's completely incomprehensible fold00:15:47
this is actually practically all00:15:50
what you need to know about what is possible00:15:52
everything is easier to write00:15:53
but remember that this statement is executed00:15:56
only number five is practically the last00:15:59
so now I'm all like this nothing00:16:06
remains magic magic magic now no00:16:13
I live, I need this in general00:16:15
fundamentally the position is generally difficult00:16:18
copy to clipboard there is something not yet00:16:21
so not so cool so so since00:16:24
where is 5th grade in short, look now00:16:29
moving to below00:16:30
the front is the coolest thing in general up from00:16:36
in its simplest form we just have them there00:16:39
signs00:16:40
correctly let's say in our case a student00:16:46
the student understands that you can do this right away00:16:49
let's call something on signs00:16:52
let's call it fps what else could it be00:16:55
frame it is clear that fromes are as if00:17:00
the source from which we select this data00:17:02
yes, that’s where we get these speakers from00:17:04
in fact you actually can00:17:05
imagine how big you are00:17:09
somehow type this big00:17:10
wide table in excel and from different00:17:13
x tables or from different excel sheets you00:17:16
pick up one big one like that, vertically00:17:19
there is a join and let's write some here00:17:24
Eunjeong is valid for groups sg00:17:32
linga and conditions according to John we will write where with00:17:41
groups a and d equal to understood yes00:17:52
look, in this example we have00:17:54
there is a student sign there is a sign00:17:56
groups in the chaise with student signs00:17:59
what fields are there at least by group de00:18:03
there exists before in the groups sign there is00:18:06
just go to the fields00:18:08
it’s clear what’s happening, something standard00:18:11
what are the types of join of00:18:16
I've heard too much inner I'll write it down00:18:20
here inner what else are there so cross00:18:23
I hear full I hear more00:18:28
elevator run and00:18:33
full left and right is actually called00:18:35
actually outer if the lead is 200 outer00:18:40
as if cross00:18:41
well, we went through it, you whine as they say00:18:44
there is a repetition of the mother of the teachings that does00:18:47
Ann is a thing of intersection in my understanding00:18:59
there is this value up to what the cross does00:19:07
cool what does full do okay let's say00:19:13
both left and right, what does the left one do?00:19:21
table which one is she here from?00:19:22
tables on the left we have one on top 200:19:24
the student on the left agrees the student on the left and00:19:29
if you what to do well as if in00:19:42
the second sign is roughly speaking for us00:19:44
if you write instead of Annie rally Tue00:19:46
there's no way back to this circle00:19:49
the request will be returned to the student who is not there00:19:52
there is no group and if I write the elevator will return but00:20:01
all fields from the group table will be equal00:20:04
why the class so now the focus is shorter00:20:11
let's not let him in; in short, I'm writing about00:20:18
student with00:20:28
cross join00:20:33
groups with SGV00:20:38
[music]00:20:39
this is the USSR with a guru00:20:46
id equals mount id what's the difference00:20:56
for a long time, leave where you are not00:21:02
look firstly the blood and it is not needed00:21:04
it's clear why because you don't need it00:21:10
you don't care about such speakers00:21:12
In general, you connect in a Cartesian way00:21:14
product of all rows on the left by Cartesian00:21:16
I’ll jump, that is, all the construction sites on the left to everything00:21:19
combinations of a string you just go through00:21:21
combinations here he sort of filters00:21:25
yes, here he tells you that00:21:28
please find it for me from the tablet00:21:31
students on Dima such groups have00:21:35
group go will be equal from group00:21:37
connects lips you will put it like that00:21:40
fit in this way00:21:41
cross doesn't need this, but there is something here00:21:48
difference between 2 queries, will there be a difference?00:21:51
output data00:21:59
some name is Jane you're right I think that00:22:04
these requests, well, if there is a scorching one to choose00:22:06
it is clear that they will eventually00:22:09
will return the same number of rows but00:22:14
there's no need to write it like that, it's true00:22:19
depends on the optimizer yes that is it00:22:21
will understand that you are, as it were, not quite as if00:22:23
well written then he will do it00:22:26
in old versions of the database it was possible00:22:29
write in general like this in short from you00:22:36
dance00:22:38
attention, groups and more are already here00:22:44
install the version and it’s like00:22:48
implied that you are doing cool and00:22:52
people wrote like this energy also don’t do that00:22:57
doing it is simply not very transparent when00:23:00
you will be from student 5 tables00:23:02
separated by commas and then in five like that00:23:06
or 15 some conditions, this is understandable00:23:11
guys got it cool so besides from a00:23:25
this is from besides join of which we are talking about00:23:29
we talked a little here maybe00:23:32
of course, just on request00:23:35
I don’t know what kind of select there is00:23:41
again the deadline even if there is also a sign00:23:48
student in no matter00:23:57
let's say nickname is equal to best, just needed00:24:06
I have to call it I don’t know00:24:10
there d yes well because you need you00:24:16
created, as it were, a new part of the request to00:24:18
and these must be called differently 400:24:27
will now have roughly speaking that the resident00:24:33
says but don’t let it be work yes00:24:37
nothing will work like that00:24:39
write something, let's say00:24:44
I don’t know the elevator, let’s say joy here and there00:24:52
write this one here as a request00:24:54
some00:24:55
he is because of jones with under requests yes he is00:25:07
will return the column we you can like but00:25:09
It’s not important to write here00:25:10
I don't know these two00:25:11
it doesn’t matter what it is, yes it will be the main thing is that00:25:17
look here the trick is that if you00:25:18
you don't have a sign like ours00:25:21
groups yes you want there00:25:26
I don't know how to count here00:25:28
something like a sum00:25:29
then you can read this upon request and00:25:32
for joe thread it here00:25:34
The main thing for you is that here in energy it’s not00:25:36
maybe not just the name of the sign, but under00:25:39
the request is a whole subquery and it contains all of them00:25:41
the same rules00:25:42
which are formed for requests there00:25:45
where is the selector for everything for everything00:25:48
it’s clear that it’s like a matryoshka doll00:25:53
yes it can be simple like this00:25:55
option but they but if someone00:25:59
tried these requests may take00:26:01
there are a hundred lines and you should00:26:07
neat I don't know define understand00:26:11
what's happened00:26:15
the meaning is there to look at the meaning of what is here00:26:19
it says only that you can00:26:21
replace the name of the sign with the request I understand00:26:29
so there's some garbage there I can00:26:30
write very useful for you00:26:32
look let's do what then for and here so00:26:36
Let's write for now00:26:45
I switch in about an hour or so00:26:49
well, let’s say I don’t know what kind of person I’ll be00:26:56
count max00:27:01
mark chrome mark s it’s clear what I need00:27:10
choose an elastic band elastic band no elastic band here00:27:22
so so so and how s.m. so here we are00:27:33
let's say the lion is joy but even without00:27:38
lion join a I'll take it now I'll write it00:27:40
here I’ll write something like boom bam bam bam00:27:43
bam bam ba I’m just writing here00:27:54
if I write just john what does that mean00:27:56
right, but try anyway00:27:59
economics writer00:28:03
so it won't work all right00:28:06
let's say it will be like this00:28:09
can we have a bison and then we arrive00:28:14
to the next part what select will return to us00:28:17
max mark is a must really00:28:19
doblo date some name let's say00:28:23
her with max mack class battles positive00:28:30
it can probably be done simply00:28:31
here then turn it over and so on00:28:32
as if they understood so much that they understood yes00:28:36
approximately look we have a sign00:28:38
ratings and I just choose the maximum00:28:41
from there not here I just returned one00:28:47
maximum00:28:49
it just doesn't matter what number you are00:28:53
you will just return a number, it doesn’t matter how00:28:55
what line did you take it will you return it00:28:57
I just don’t know what the maximum rating is00:28:59
for some reason an A00:29:02
let's say hypothetically and to all records00:29:07
from here you are with a joyner in this case alone00:29:12
record with these five00:29:16
max mark well, here I wrote spring00:29:19
It’s also clear we can give me a wife00:29:22
they write there00:29:23
here you can tell the quality here00:29:25
yes, you can go to the conclusion00:29:44
there's nothing odd the screws it00:29:56
nothing until some kind of deception and license plate00:30:03
just fooled where00:30:09
mmm so save money well damn it started00:30:18
so I think I can move this thing00:30:22
in general, endlessly, okay, the meaning is clear00:30:29
the main thing is to understand what it will be like00:30:36
and can be accessed through00:30:39
or through simply00:30:44
mmm mmm or look if we have00:30:52
other tablets have no more columns with00:30:57
name00:30:58
m m which is very likely then you can just m00:31:03
m on that is, you use with this00:31:06
prefix with this here is a letter only00:31:10
then when you want to indicate from which00:31:13
signs you want to take, let's say if you have00:31:16
groups have a name and students have a name00:31:18
and when you want there I don’t know to pull out00:31:22
you will need to specify00:31:23
With . name or g.na in this case it’s clear00:31:32
yes of course that's the point, that's why00:31:35
we them we we gave it a name with a g there and00:31:39
this one here so that later from them always00:31:41
from a specific plate it was possible00:31:43
ask for names, that is, some columns00:31:46
identified by name, that is, they are all00:31:48
begin to apply them with new ones00:31:52
I understand guys yes yes yes here too00:32:06
Of course it is important how the optimizer works00:32:09
will he really count alone with this00:32:12
the maximum that is actually practically00:32:17
the other must be like this before either he00:32:21
will start type for each line and00:32:23
subtract this one for the request and so on00:32:25
similar things but look at this one00:32:31
let's complicate the request a little00:32:33
write here vr is acceptable00:32:38
groups ID is equal to this to the deputy also m.m.00:32:46
guru00:32:47
go boom it's clear what's going on look00:32:54
what happens these requests immediately00:32:58
the so-called steel turned into00:33:01
correlated and the request, that is, here it is00:33:04
build such a multitude of students with their00:33:07
groups and now to him for each group00:33:12
where you will need to go to the ratings table and00:33:16
find the maximum score for this00:33:19
groups and and with John with all these lines00:33:25
I generally understand what I said, I don’t see00:33:29
it’s just in your eyes that you look wow00:33:31
here it is here there is always one quickly to00:33:37
here there will always be one line per00:33:39
due to the fact that we called max00:33:46
this can be implemented differently in00:33:49
principle for each group for each00:33:53
this is the group he should be00:33:56
do this upon request and even if00:33:57
add it to us a little bit and00:34:00
you will receive a student grade and00:34:03
maximum in his group00:34:05
well, that is, not any student’s name and00:34:06
maximum in his group why is this00:34:08
we need to, let’s say that’s what we have00:34:11
we realized the requirement, Igor, let’s not do it yet00:34:15
I understand what exactly you get00:34:32
line00:34:33
let's say a student and he will be in a group00:34:36
go now you say yes maybe you can00:34:43
think that so for each line you00:34:45
ask00:34:46
that when should you take the ID00:34:49
from the boom group sign from here and00:34:53
calculate and find the maximum for it00:34:55
look at the assessment and put it into practice00:35:04
for example, if the group sign is small00:35:07
yes, he will moan and take all the lines00:35:10
from the group sign will find everything for them00:35:13
highs about now he will get a sign00:35:17
group of ideas, at most there will already be00:35:22
gather with students, that is, he does not00:35:24
it would be like starting with the students, yes00:35:26
like starting with a smaller sign00:35:28
for which we actually have to00:35:30
calculating this maximum is understandable00:35:33
guys who didn’t understand my main rule00:35:42
it's normal that there are no lectures00:35:44
I understand, yes, that is, this is necessary00:35:45
I confess I will repeat it to others00:35:47
speak in words and so on00:35:52
correlated yes and when he refers to00:35:58
another sign you're full xs00:36:01
correlated, you understand that's it00:36:02
this is this this is this this is what you are00:36:05
Gillian pointed out and here here here00:36:07
there is g yes you took it you tell him that you are here00:36:10
upon request, as if forced to be00:36:12
related to this yes if so if there00:36:20
been there for a long time well yes yes if you were there VR00:36:22
let's say I don't know there go equals 3 then00:36:28
all this is the same request that can be00:36:30
perform it once as if yes and nothing00:36:32
happens because we forced it00:36:37
it's easy to look at this sign00:36:41
will be forced00:36:42
for each of this group calculate00:36:45
this maximum and connect it to us and00:36:46
give it to you, look at it like this00:36:53
since it is called relational thinking then00:36:55
there, look, how would we add it to00:36:57
Javit or I don’t know the java script I absorbed00:36:59
they are there who writes what00:37:01
basically some kind of scripts we always00:37:05
opilio drank we appeal with commands to00:37:08
actually, like, I’ll open the refrigerator00:37:09
take the milk, I'll open the traffic jam in the alley00:37:12
We'll close the milk there, put it there00:37:14
refrigerator close the refrigerator and like this00:37:15
we write code from the point of view of isku elia00:37:19
we tell him please give it back to us00:37:22
Cup of tea00:37:25
it's practically declarative, that is00:37:28
It’s as if we’re not quite declarative here00:37:30
simply because the declaration is too00:37:32
It’s difficult and sometimes it works, but in fact00:37:34
you yes you tell him please give it back00:37:36
this is what I wrote to you here:00:37:39
he will do it00:37:40
this is what optimization is all about00:37:42
what indexes does it have what what how00:37:45
we'll ask for it because it's the same thing00:37:47
we can ask in completely different ways00:37:49
yes, roughly speaking, this one here00:37:51
this request request we could00:37:54
put actually in select right in00:37:56
fields remember I said what’s there in the field00:37:58
you can write that is under just the same00:38:01
request from lace and to remove and put00:38:03
in select00:38:04
as a result, nothing would change as00:38:07
would have processed the request unknown you didn't00:38:10
did you understand, look, we could write here00:38:14
too much board manipulation needed00:38:16
I'll have to do it here but00:38:19
we could write like this: select any i00:38:23
I'm just not thinking well00:38:28
It’s not like, well, it’s bad and I use it00:38:31
this one is on request and then Frol and you00:38:37
even here all the freaks00:38:39
nothing would most likely change00:38:43
that is, we could indicate in the fields under00:38:45
leave the request as I indicated from rome00:38:48
our field would be the same now00:38:50
correlated with the request00:38:52
it's just another not a few friend00:38:55
slightly different record of the same request00:38:57
in fact they would bring at least one00:38:59
and with the same data, at least something is clear00:39:06
we will practice but this is necessary00:39:12
of course it takes some getting used to00:39:19
so let's move on because00:39:22
we are all moving towards you know what is right00:39:26
kingu t t t t t t t t t t t t t t t t t00:39:33
were probably not very cool anyway00:39:35
boom so now so so so00:39:43
Now I’ll erase it, by the way it’s not multi-touch00:39:47
or multitouch no or multitouch somehow00:39:50
somehow not too close well00:39:53
ok so everything next is in our00:40:04
the simplest thing I think is simple00:40:06
filter yes how we want to make a filter00:40:10
it is clear that in r everything can be the same00:40:16
the most practical thing is that the selector under00:40:19
the simplest ones can have requests00:40:22
let's say name I've already done it a thousand times00:40:25
but it’s clear Sergey himself is a simple filter00:40:30
date is acceptable or 1 is equal to 1 of it can be like this00:40:43
write to you here will be true of course00:40:44
will always return all rows but00:40:45
potentially it's possible so it's not00:40:47
we'll do it, we'll erase it, it might be under00:40:54
requests00:40:55
let's say some, let's say the most00:40:58
the most famous frequent case00:41:02
you are intrinsic poke poke poke we will erase or00:41:06
let's say00:41:08
so now boom boom or00:41:12
well we choose let's say chrome students00:41:16
our students with s and write where00:41:25
This is how I write VAT.00:41:30
group of ideas then I write this and boom00:41:35
boom and I write select00:41:41
group go00:41:43
or not even a group, I’ll erase the offense now00:41:48
that's all yes I'm for and die from the guru's00:42:01
let's say it will be called by the way00:42:04
you can often skip it, but it’s better this way00:42:05
it's better not to write from but you can00:42:07
just write groups00:42:08
and type this and issue it as an alias where00:42:11
let's say00:42:14
could get is equal to I don’t know what we have00:42:19
faculty on cool TNT, well, it doesn’t matter 200:42:29
look it's clear what's going on00:42:36
great who said not very handsome00:42:39
something is the name, look, Arsenyev is there00:42:42
short00:42:43
7 here's seven look in short we're returning00:42:46
all students00:42:47
where the name is ravens and the name is equal to Sergei and00:42:52
groups fields group go00:42:54
from the sign student student enters00:42:58
list00:42:59
boom and this list returns us under00:43:03
a request that tells us return everything00:43:06
disks from the group table for faculty 200:43:12
you will return here only a group of this00:43:15
faculty00:43:16
and then you will return only people with00:43:18
named 2 yes yes yes look in the standard00:43:35
I'm sorry, as far as I know there's only one here00:43:38
column maybe but yes but00:43:43
If I'm not mistaken, is it possible?00:43:46
return two columns well in short00:43:49
some implementations can have several00:43:51
columns to return and there, as it were, already with00:43:53
work with them but look at standard 100:43:55
what trick can you do inner join yes00:44:00
yes exactly00:44:02
absolutely true that is, yes and it will be00:44:06
the project is the same actually00:44:08
almost the same thing, that is, we can00:44:09
take this request put it in frome00:44:12
here let's just say everything is the same00:44:15
do as as upon request leave it00:44:18
and it will be almost the same as us00:44:22
we can even just for Johnny Tsana group then00:44:24
there is write from you dance00:44:26
here I will write like this inner join00:44:30
groups then write it in groups go00:44:36
and then write md groups faculty00:44:42
equal to two, I understand, but it’s not clear, yes00:44:49
yes, that is, it’s not easy, but it’s like that00:44:54
you don't necessarily have to link to00:44:55
previous sign with maybe a piece00:44:56
filter yes, that is, here it is here00:44:59
posted here here it was possible00:45:01
just write in three lines just for00:45:04
johnny prices for groups by group well by00:45:09
students in a group but leave here00:45:12
there is only a group of 2 faculty here00:45:16
Is it clear or should I be stressed and00:45:19
write it more clearly but not here00:45:25
it is written that we are returning here we are00:45:27
we just work with a set of strings they give us00:45:30
the set of lines will be the same until00:45:38
right, if we don’t choose them then00:45:43
most likely will not appear no will not affect00:45:46
look rude if we write here00:45:48
select to select with . asterisk off00:45:54
so it’s also possible that this means all fields00:45:59
from the students' sign yes yes why can we00:46:04
use abbreviation because00:46:05
select works after from a yes that is00:46:09
the first one will work frome he is already in this00:46:11
moment we find out how we tell them about Olya strength then00:46:14
there are some we came up with for them and then00:46:17
we will return them to this time accordingly00:46:19
moment we just asked for all the fields00:46:21
the only difference is the only one00:46:24
difference in and and inner join a and here you need00:46:30
now straight away strain that inner00:46:33
join can increase the number of students00:46:38
there is no need why why is it correct the other way around yes00:46:44
firstly, if there are students who00:46:47
no group00:46:48
then we will lose them, but most likely we would00:46:50
and so they lost because the warrior was but00:46:52
if there is if let's say there are groups with00:46:59
the same IT guy on this plate00:47:02
groups it so happens that there are 26 groups00:47:05
you sit down with nickname 2 and group 27 you sit down with nickname00:47:08
2 there and for all students with this00:47:11
The IT guy is bifurcated, understandably because00:47:16
that's how it works00:47:17
inner join yes we are for each00:47:20
records looking for matches but if you dig00:47:23
if one tablet contained one line in00:47:25
the other two lines we will get two lines00:47:27
so if like VR and never like that00:47:31
will do it just filters it doesn't do anything00:47:33
propagated, that is, it will simply filter out00:47:35
to us, yes, all this is the transparent logic of the son in00:47:39
john if you are johnny looking for keys00:47:42
I bet the key will be ok variant entry00:47:45
and the optimizer will understand, but if you00:47:48
get married, don’t connect me using unique00:47:50
key and about something else00:47:52
then theoretically you can increase00:47:54
number of entries in well students00:47:57
return there I don’t know there was one Sergei you00:48:00
return just doubles boom-boom-boom-boom00:48:03
Well, it’s hard to say something literate00:48:14
John in short he is transparent revered00:48:16
a person, most likely yes, but this one is just00:48:19
it’s clear what you want to do and what you want00:48:20
it's also ok to filter00:48:22
it just reads a little bit more00:48:25
bulkier than this one00:48:26
and if we let you, look at the trick00:48:29
without yes as you asked here in the past00:48:31
about several fields like yes yes then00:48:37
there are faiths here we always filter00:48:39
let's say in a group and always one at a time00:48:41
field then you world join and we can write00:48:43
one field at a time and then write and00:48:47
something on the second field too, yes then00:48:50
there is an inner join here, just more00:48:55
a universal way to do this if00:48:57
Let's say you need not only in a group00:48:59
dead filter and return from everyone there and00:49:02
from the faculty and there some other one00:49:05
take groups and then, well, in short, two at a time00:49:07
fields you can do it here00:49:13
I'll have to write another one then00:49:15
request that is, write if vr and00:49:17
will leave u let's say write n.s.00:49:20
name in duplicate this request00:49:23
get the same field and it will definitely be there00:49:25
done twice, most likely this00:49:27
piece this piece this has a chance00:49:29
will be executed once transparency this but00:49:35
this is exactly what I need to say here00:49:39
feel it and it’s not a fact that it is00:49:43
everything will fall very easily at once, it’s like00:49:48
it would be ok to actually eat00:49:52
there is a certain art to writing select but00:49:55
when you write there are already dozens of them00:49:57
then something will come to you and I don’t know00:50:05
which lens is object oriented00:50:07
programming yes, that is, there is such a thing00:50:09
Taman shift which you overcome and00:50:10
then it becomes natural for00:50:12
these little classics are all sorts of things for you00:50:15
patterns and so on, see rough00:50:18
roughly I write simple USA in the simplest00:50:20
the query we wrote select max00:50:28
Mark00:50:32
from mark00:50:37
there is such a thing as00:50:39
I am using the aggregation function here00:50:43
max yes they are max help me00:50:47
close what other count and in g and food on00:50:57
they forgot one of the most important things, cult okay00:51:00
I'll help you with the amount, it's like basic00:51:05
accordingly, these are always some kind of grig00:51:09
tion functions are applied to the group00:51:11
when the group is not specified it is considered that00:51:14
all00:51:15
the entire set of rows is group 100:51:19
accordingly this request means I00:51:22
I want to return the maximum rating out of all00:51:24
rating table00:51:26
yes, if I write it like this00:51:30
groups bike let's say group go and here00:51:41
here I’ll say I’ll write it like this00:51:45
group go what will it mean to00:51:52
that means yes, that is, we will take everything00:51:58
We’ll break a lot of estimates, open the window and00:52:00
at some point it becomes stuffy mega00:52:02
rs load falls asleep and we are still heavy00:52:07
nbu didn't get there00:52:10
so you will tell me if I will close it for him00:52:14
we'll take a break so watch this00:52:18
means that we will break this multitude00:52:20
go to groups according to the field and in each00:52:24
from these groups we will take the maximum00:52:28
we realized, yes, and accordingly we can00:52:30
also take the sum of these estimates into the average00:52:33
from these estimates and so on he will return to us00:52:38
as many lines as the group de00:52:40
was well, in general, if it’s not allowed there00:52:43
there was no recording he will return us nothing everything00:52:54
but he will just return 0 yes yes yes but00:53:07
these are the columns, look at this00:53:12
right now I want to slow down until the column influences00:53:24
only on the order of columns in the village gti then00:53:28
yes you will change them accordingly00:53:29
you will receive a sign that first00:53:31
there will be an ideapad group and a maximum one00:53:32
grade00:53:38
rough00:53:39
across the field in a group so look great00:53:43
what's the name of the novel look here let's say00:53:46
there is a scoreboard for you, look in the sky00:53:48
the letter is written by a student, poor, etc.00:53:51
group go assessment student group asia00:53:55
there are a lot of assessments there00:53:58
let's just write it like this, look at it00:54:00
we have let's say it doesn't matter group go00:54:04
Mark, well, it doesn’t matter, we don’t have it yet00:54:09
fundamentally here too00:54:13
122300:54:15
here 435200:54:21
accordingly, we will return how much00:54:30
lines first we will return let's start with00:54:32
This and three lines is correct Arman come on00:54:36
next what lines will this be a group00:54:40
let's just have these lines, how's that?00:54:46
since we don’t talk and there’s no order00:54:48
ours were determined in any order in any00:54:50
ok Victor look we won't refund00:54:57
which of these lines00:54:58
Yes, we will return as if the new lines are not00:55:02
according to plan. no matter how we do it it won't be00:55:04
none of these lines of code we will return 1400:55:09
25 and 32 3 new lines00:55:15
if there was any amount there, we would return it00:55:19
1428 32 no, he would return one to us00:55:35
us00:55:42
what he won't understand perfectly why you don't00:55:47
I said before, that is, before that pocket00:55:50
asked did you understand00:55:51
and now no, let's have four lines00:55:57
we are a group, look what grouping means00:55:59
yes then we group it means that00:56:03
we break them into parts with the same00:56:07
the value of this field is that we have00:56:10
it turns out 1 group 2 group00:56:13
and then the three group realized what your name is00:56:18
I understand the tapes, yes we are grouping, we hit it00:56:24
group go all groups are lines y00:56:29
of which this field is the same00:56:32
file fire handsome Lena everything and then to00:56:38
this group, that is, to the lines from this00:56:40
groups, apply the function accordingly00:56:44
which we took and take max from here00:56:46
max due to these values max due to these00:56:48
values00:56:49
either the amount or and HIV or the minimum and then00:57:05
there we will do it here we write here00:57:13
like a comma and write here, let's say00:57:17
minimum from mac00:57:21
you're just so smart bottom how simple00:57:36
musical effects everything is booming00:57:40
So00:57:45
come on, of course, always any00:57:52
aggregate functions apply to this00:57:54
game peak lines from this group and you00:57:56
you will return the maximum for some reason later the group00:58:00
go then at least if not in rude00:58:10
there can be any number of columns00:58:12
see here it may be acceptable if00:58:14
I'll write a recording group let's go00:58:18
look, we have a sign here00:58:20
we now look we have00:58:24
score board give a good question00:58:27
well done we have a mark sign in it00:58:31
we have an ID column let's say groups00:58:37
city and mark boom-boom-boom like that00:58:42
like this and now I'm taking this look00:58:46
tricky now about what else will I get, and00:58:57
what will it be let us assume that it is00:59:04
yes, this will really be the whole sign and00:59:08
the maximum and minimum will coincide with00:59:09
Mark himself can write this00:59:15
you can write transparently until it turned out00:59:17
something like this will be a lot of groups00:59:24
in fact because you have these unique ones00:59:26
All00:59:27
yes and it turns out well how well yes it be00:59:29
a lot of entries00:59:30
you will return a lot of records because there are a lot00:59:32
groups you have like groups one group00:59:34
will be equal to one line00:59:35
let's say you can write00:59:38
rude mark, well, I don’t know, it’s just00:59:42
have to00:59:43
[music]00:59:45
throw something else here and there00:59:48
you just have to change something like this00:59:50
it won’t work out in short okay we have all three00:59:54
columns, as it were, but the point is00:59:56
as for01:00:02
let's add fk id then you can yes01:00:08
write efco here01:00:10
go, bruce in theory but here the trick is on01:00:15
in fact, look at the castle like that01:00:17
worth it is important you can choose in the village01:00:21
gti01:00:22
which columns is a problem for an A?01:00:28
what columns can you write in the village01:00:32
gti01:00:33
on the contrary who is a rude fellow01:00:37
Egor is great, that's right because you are01:00:39
you can write only those columns according to01:00:41
which formed the group01:00:43
others you seem to be sorry and neglected yes01:00:47
that is, how would you imagine that you01:00:49
like how like this is like the simplest01:00:51
way to write rude here you have it01:00:53
list of objects you take to the USA01:00:56
enter the keys from two fields, not in the hash01:01:00
this yes there with these yes let it not matter in01:01:03
hash table means yes and you run01:01:05
through all of them and when you find a new one01:01:08
you insert the key there and yes and let's say01:01:10
depending on aggregate functions or01:01:12
there at most you read either the amount or01:01:14
average on like this but with average there01:01:18
it won’t work out like that, no matter how01:01:21
you would accumulate it like this and01:01:24
work accordingly then when you01:01:26
they ask you to show everyone else01:01:29
columns except those for which yeah01:01:30
the banks were in the lead, respectively01:01:32
tion functions were lost accordingly01:01:34
everything is easier with rough can participate01:01:36
only those columns on which I was01:01:39
rudely01:01:40
it is important01:01:44
optional, you don't have to add them01:01:46
roughly speaking, as in this case, look01:01:49
if the group belongs to the faculty well01:01:54
like in a normal university you are a group01:01:56
studies in the same department and in the same department01:01:59
it is obvious that grouping by01:02:04
fk adi she is redundant because more01:02:08
rigid grouping by group ideas01:02:11
understood01:02:13
Wait, did you realize that you were watching?01:02:17
we will have such a topic that these are all in01:02:20
first faculty but group 3 in01:02:22
second faculty but the groups will be all01:02:24
like this one like this maybe up to01:02:31
maybe of course maybe of course maybe01:02:33
maybe I'm just talking about our specific case01:02:34
I say when this is the faculty of course they can01:02:37
there may be differences, yes, well, if it is01:02:39
faculty and this meaning is simple01:02:41
you have a wider group anyway01:02:43
it will be, as it were, in connection, well, that is, you01:02:45
the two fields will have to match because01:02:47
it's always kind of the same, that is01:02:49
you will still be in the same groups and01:02:51
you will get the same value but so that01:02:53
take him out01:02:54
faculty go you'll have to add it01:02:56
here so you can write here01:03:00
faculty or01:03:02
yes yes no you view correctly like this01:03:20
The trick is that in the aggregation functions01:03:23
you can use all the others01:03:25
fields inside aviation functions in max01:03:29
in total, that is, that's the point you should01:03:31
collect groups but with these values01:03:33
with the rest, use some kind of them01:03:35
gravitational function sum average there01:03:37
it doesn’t matter what it is01:03:39
inside inside max you can01:03:42
use only you run shorter01:03:44
you run to your sheet, you run, you run, you run01:03:45
so yeah it's a new key what's the matter now01:03:49
with these values yeah I add to the sum01:03:52
previous key riot folded ran01:03:54
further but as soon as01:03:56
ran on, you seemed to have already lost everything01:04:00
worth no order may not be maintained01:04:06
imagine what you wrote01:04:08
algorithm through there through a hash table yes01:04:12
and in the end you collected everything like this01:04:14
we've gone through the entire list now you need01:04:16
run through the hash table and there it is01:04:17
may be there already in any order then01:04:20
there are times we ran and you gave because01:04:22
in fact, we don’t give him any order01:04:24
indicated here if we wrote here01:04:26
here's what we'll talk about next warrant01:04:29
buy let's say by faculties he would be like this01:04:32
tensed up were still on you and01:04:34
you need to sort by faculties okay01:04:36
asked me to do this in the table01:04:42
no unless you ask for it through a warrant01:04:46
buy the you can get it or maybe01:04:48
you won't get any01:04:50
no guarantees look yes he can avoid01:05:02
sometimes sorting if he already understands01:05:04
that they will turn out in this form, that is01:05:07
the sorting operation itself at this moment01:05:08
won't that is if if they then don't01:05:10
I know on the disk they are stored in groups01:05:15
he knows this before he controls and he seems to01:05:17
there is no skip sorting operation itself because01:05:19
that it automatically has groups like this01:05:20
it turns out they understood that he was gone again01:05:30
as if but it seems to be out of order01:05:34
they, well, look at this to the question about the index01:05:47
let's leave it for later but01:05:51
in fact I just wrote them down like that01:05:53
they could be stored there fasting to me like this01:05:56
absolutely that is, if you the main thing is that01:06:01
you need to know if you want what order01:06:02
then you need to ask him to sort it out01:06:08
if we have two and two01:06:13
if allowed by group 92201:06:18
that's a great question01:06:22
orlam Arman, well, it’s okay, I could be wrong, I01:06:27
I'll remember you Arman what we'll have01:06:29
results with function let's say max as01:06:35
do you think how many groups there will be here?01:06:39
in short here you kind of know01:06:41
everything is written hard, look at forty01:06:43
four lines here four lines 1101:06:46
12 22 2301:06:50
how many groups will we group by01:06:54
two fields on these, this is what I called it01:06:56
Let's call faculties 1 and here the group is not01:07:05
field and how many groups will be incorrect01:07:11
us last time when we grouped01:07:12
there were three groups in one field, now we01:07:15
In short, we group the fields into two, we already have01:07:18
it can't be less than 301:07:21
these groups and which used to be 11111101:07:29
group 1 2 next group 22 and 23 to01:07:33
because not everyone of course is a group01:07:37
which has the same value if01:07:40
this is one column means one column at a time01:07:42
if two columns two columns neva you01:07:47
four groups up to 4 groups the same01:07:51
how many lines does this example give us?01:07:53
we have one more line which is there01:07:55
if there are 12 then there will also be four groups01:08:00
that is, unique couples are really here01:08:03
in fact, that is, the group will be created for01:08:06
each has a non-unique pair of columns01:08:15
it's not crossing it's nothing it's just01:08:18
you sort of group them by unique01:08:23
with this unique coincidence of columns01:08:25
and for all of them you count something01:08:28
I say that’s what you do the key in01:08:31
your hash table, now you have made the keys01:08:34
1112 and 223 and apply to each of01:08:37
keys first let's say we made a key01:08:40
saved all the values, turning them off later01:08:42
all this sheet that was saved01:08:43
use some function and return01:08:47
it doesn't matter if you question me01:09:00
interested in the third row guys in nothing01:09:02
ask and I'm worried ask me01:09:05
anything let's say my favorite light01:09:10
bonfire weather will be in some places generally01:09:14
ok okay and we're straight ahead01:09:20
we are moving in steps in the right direction and towards01:09:24
take a break, watch about the Winx fairies, Lyokha no01:09:33
wait I'm not the leader01:09:34
you go there and then you'll be everyone01:09:38
we'll tell you even hank didn't tell01:09:40
so passed look healing like me01:09:48
already said01:09:50
healing people write in the career a couple of times I01:09:54
as if I’m telling you that’s why I often and01:09:56
I'll write out 301:10:05
that's what having is, do you understand?01:10:11
that's it, look having this is a filter01:10:17
which can be imposed on01:10:19
some kind of aggregation function and01:10:23
filter the groups we have01:10:25
turned out after a rough one, that is01:10:29
look at us there, let's do it one more time01:10:31
our sign one is acceptable is acceptable01:10:35
even we have one field group go and01:10:37
Now I’ll fix it all so that we don’t01:10:39
suffer too much 3 come on I want you01:10:43
I'm tense now it's important I'll ask you01:10:45
then you yourself know in the exam those01:10:49
and wink01:10:50
Of course, a thousand guys will have me even01:10:57
didn't ask for anything wait I haven't yet01:11:00
I managed to ask nothing even to look01:11:02
game go we have one here let's say 301:11:05
here October 2 here 4 here 2 here 501:11:11
here there are three here let's say 4 yes this is01:11:19
ratings this is a group go01:11:25
how many groups do we have 301:11:29
initially further we received for them01:11:31
lines let's say we think well let's say01:11:33
how would we rush to having - we will rush01:11:35
we calculate the average we calculated 3413 and that01:11:46
24 and a half before he realizes that you01:11:52
somewhere there except so that it doesn’t matter and01:11:54
now we do having heaven says01:11:58
please give me back only those groups01:12:01
whose average score is more than three is01:12:04
that means we will return groups34 24 and a half01:12:13
more than three.01:12:15
that is, we will return 13 and after that, actually01:12:18
in fact, we want to count the maximum of these01:12:21
groups and in fact we will return well01:12:24
almost the same thing you use 342501:12:33
such having now why no one01:12:37
writes having no come on Igor man01:12:40
I thought because you choose the maximum01:12:47
and you filter by a in d you see having a01:12:51
v.g. and you choose a topic like this at most01:12:53
the cunning one easily came up with it but so01:12:56
seems to be decreasing now why isn't anyone01:12:59
writes having clear it was drawn01:13:03
yes because any request is healed01:13:06
can be rewritten via v.r. that is01:13:09
I accept this request01:13:11
I’m writing like this, here you are opening the boom01:13:14
lines start close called adele01:13:16
I’m writing in and in the game, also here of course01:13:22
I think a in g mark is called a let's say m01:13:27
and I'm mad V.A.01:13:30
yes more than three and in the village I return the GTI01:13:36
only this is the maximum up to01:13:40
it is clear that this is not so compact01:13:44
yes we had to this one here this one here under01:13:46
wrap the request here and replace having01:13:50
no where yes it’s clear what happened01:13:57
here are the members of the dog01:14:00
yes, here it is, as if I wanted to, as if I was01:14:02
still passed something to count01:14:04
I asked him to count 301:14:06
aggregation functions one at a time01:14:08
filtered through 2 and returned 201:14:13
yes they all are better for me just having is possible01:14:15
not only you and everyone don’t know that’s all but01:14:20
so well yeah he's just like you have01:14:23
the opportunity to write a request is simply here01:14:26
like this, not nested with one level01:14:29
nesting yes, here’s how to write it01:14:32
yes, this is where you get it01:14:35
the request is somehow nested but01:14:36
there is potentially nothing to do there01:14:42
considered bad, but people just don't01:14:46
no tradition you write prostate01:14:49
nickname you've been writing this for 1 year because01:14:51
you always think within the filters yes01:14:54
so I need to calculate then I need to01:14:56
isolate what can be filtered out01:14:57
for aggregation functions only01:14:59
gaming as it were, oh my God, how could it be01:15:03
it’s as if he actually remembers everything but01:15:04
almost no one ever writes write01:15:06
there was a request for this and away we go01:15:13
look at him in short, here I called01:15:15
So then I named these speakers somehow01:15:17
here I selected them and here I understand to return them01:15:24
yes this is it from select asterisk this01:15:27
from everything correctly noted this one is good01:15:31
under select then vr then from here01:15:34
columns were filtered one by one01:15:36
the rest were returned here01:15:41
I don't know if anyone will find the request01:15:46
which cannot be rewritten01:15:49
without Haring, well, I don’t know, from me automatically01:15:56
come on, if you want a machine gun, come here, yes01:16:23
you speed up, it probably depends01:16:25
temple imitation but don't wait at all01:16:35
why did you endure like the first one just synths01:16:38
tolerated yes yes well at the level so here01:17:03
it is important from this whole logic that it is not equal01:17:06
nalu01:17:09
yes that is, what I didn’t tell you yes that01:17:13
eat as if you want01:17:15
filter and return only to us boom01:17:20
boom boom boom boom boom boom boom 5 to then01:17:30
there is another one if you need to leave01:17:31
only mean01:17:40
it's all in one column of all kinds of [ __ ]01:17:42
it is written that you will go there somewhere too01:17:44
you will read Marx line by line01:17:46
I'll tell you dude I can't count it there01:17:49
come on, let's fall for you as if for everything01:17:54
the rest depends on the editors who01:17:56
you will write it if you go there01:17:58
let's say something on the table01:17:59
I don’t know the maximum that you can do01:18:01
substitute it can be said more often01:18:02
today look what's important and what I don't01:18:05
told me that if you want01:18:07
filter let's leave in01:18:09
on the plate we only allow the values01:18:12
you can write permissibly go and from to01:18:18
either from01:18:20
but that is, we have to check01:18:27
special operators because if01:18:29
two columns equal to us this will return01:18:34
permissible lion01:18:38
that is, nalu is not equal to us01:18:42
that's so clear it's boom boom boom boom01:18:50
boom boom boom and we only have a warrant left01:18:54
buy then take a break01:19:02
Then01:19:03
I’ll tell you again through I ask you sakan apa01:19:07
time later this sedge early 6 3001:19:12
pieces we still have time left class01:19:16
I'll ask you a lot more, so look01:19:21
the buy order is the latest to work01:19:26
it’s clear what he’s doing, write a buy order01:19:32
you get all the lines sorted01:19:36
by name01:19:38
write them correctly in ascending order01:19:43
initially ask for default yes no01:19:48
nothing just exists, as it were01:19:53
increasing01:19:54
ask ask standing and descending will give01:19:59
standing compare or comparator type01:20:08
right up to here everything works from this01:20:13
everything is too deep there actually01:20:15
actually goes into some lines01:20:19
invar char did not tear the char how are they stored01:20:22
let's say it can compare registers01:20:25
dependent may case independent so01:20:28
gives you something similar, that is, it’s all on01:20:30
in fact, then it goes deep into01:20:32
implementation and let's say I don't know if you have01:20:35
one has a name and the other has a name and then they are there01:20:39
can01:20:40
in one case be generally equal and if01:20:44
I don’t know where you are talking01:20:46
something else big and small letters01:20:48
considered the same, that is, case01:20:50
the intention of those that is insensitive01:20:52
The register can sometimes be uneven01:20:54
if you are sensitive and rivers of registers01:20:57
there are also all sorts of accents c above letters01:21:00
yes there are some letters like this01:21:04
then, well, in short, this is all bullying01:21:06
Russian people accounts01:21:10
Yes, accordingly, you can use a buy order01:21:13
write to mts write down, let's say her01:21:18
name01:21:21
ask yes yes yes yes look what is important you01:21:38
you can even write a case study yes01:21:42
that is, you can write everything there01:21:44
this is completely case expression and01:21:46
it would be good to sort them by this01:21:58
tu tu tu so wait so look01:22:10
example on01:22:14
case you01:22:20
equals01:22:21
to cut smoke 11 1 of 201:22:32
Well, I sort everything first by name01:22:35
then by last name and then by 12 and one01:22:41
only for names that are equal to that01:22:47
more like these nestings01:22:49
sort groups01:22:58
one more than two really caught you01:23:05
just before01:23:08
we sort simply therefore it means that01:23:11
we sort by these columns, that is, well01:23:13
let me even delete this one just so that01:23:15
didn't bother me01:23:19
I’ll delete this now, it will be simple01:23:21
see the thought means first01:23:25
no earrings01:23:30
so look here we sort by ask01:23:34
yes it's like ascending that's all01:23:37
time is hard first for the little ones01:23:38
they will all get there first, Seryoge, well then01:23:42
there is everything with and then everyone else yes you01:23:47
that's right, there's not much to do right now, nothing about anything01:23:48
I just think slower than you all this01:23:52
it's okay if I write here01:23:54
disk before then in short everything will be the other way around01:23:59
and accordingly the complexity of the expression here01:24:02
maybe, well, in general, who do you like?01:24:05
anyone for requests in a buy order01:24:10
you can’t write, but you also know in short with01:24:13
the coolest feature in the selector come on01:24:19
quiet little guy married to live like everyone else01:24:24
name is glory class just for you just01:24:33
will be after with yes yes well look if01:24:39
I’ll write it like this for the type but if so01:24:46
so I’ll write thank you, that is, if that’s it01:24:50
so I’ll write on and01:24:51
then all the deuces will be named01:24:53
sorted and if I don’t write anything01:24:56
it means that the order after is not important to me01:24:59
of all scales of course they will first01:25:08
all those with and then by name of course01:25:16
well, in the forehead yes yes but only that01:25:23
will remain but wait a minute look here01:25:30
us quietly sub-point let's go straight01:25:32
this turned out to be such a difficult question01:25:35
give we have a name in it there is and there is01:25:41
words there are with there are Alex01:25:49
why are words and alex not even here?01:26:02
I understand the question, wait, look, let's01:26:03
how will this be sorted01:26:05
how will he no we would say no01:26:07
just 1 Caucasian that when the name is equal to01:26:10
yes of course we didn’t write here there01:26:13
I know like cinque what a promotion is01:26:15
titrate the number highin tochnyak yes now01:26:22
well done prophet remembered reminded me01:26:24
Now I’ll tell you a little about her too01:26:25
it means the beginning comes with bu da disk or disk01:26:30
no disk disk ours with at the end you know God01:26:35
my we all have a drink now I'll fix everything01:26:43
well, with and then by name then it means01:26:48
it started difficult, who first and01:26:51
or alex but I think and then alex glory01:26:57
forgive me please01:26:58
or you can't say that he says01:27:00
words forgive me please words forgive me01:27:07
please then you I didn't do it on purpose.01:27:16
now in short we will write a disk here yes01:27:18
wait disk you know by date in short everything01:27:23
it's all clear and gone in short01:27:26
till the very first let everything be01:27:36
on the contrary then the question is if here01:27:39
write three I am here write two in01:27:41
in general it is clear that nothing is good01:27:43
such a request will not work, well, I mean01:27:46
turns over means well of course you can01:27:49
write a house here, I don’t know, yes you can01:27:53
count -1 can write words here01:27:55
or there Alex anything I just01:27:57
example written about the league is bright now01:28:05
let's talk and ask us 3 rows01:28:27
well, when order is important to you then you01:28:30
order is important until roughly speaking01:28:32
there are goods in the store01:28:34
click I want to watch the biggest01:28:37
prices and then the first 10 screens just01:28:40
scrolling through how we would look at them01:28:43
how does her cool track start?01:28:45
the most expensive no let's go to the second sheet no let's 301:28:49
maybe here I can afford it01:28:51
but there on the last sheet you buy like01:28:54
would be second from bottom01:28:59
yes of course of course of course it's a ride01:29:01
of course not, at best he is his01:29:12
will let him through, that is, if he has data01:29:15
will be sorted in that order in01:29:16
ok he'll just skip the surgery01:29:20
and will understand that she returns so much in this01:29:21
ok01:29:22
otherwise you'll put some strain on him01:29:24
sorting always therefore if you01:29:26
no need to sort, no need to write it01:29:29
if you're there I don't know if you get this data01:29:32
then you load it, I don’t know, just hash tables01:29:37
I don’t know why it’s there or you just don’t like it01:29:40
it is important not to process them in what order01:29:42
you have to force him to sort it for you but01:29:44
if you let your algorithm be there too01:29:47
depends on the order I don't know you're running there01:29:50
to all the similar groups there01:29:52
do you fold something else then strain it01:29:54
order for networks how the class will be convened01:30:05
yes yes of course of course yes see question01:30:15
he was so beautiful I read with some01:30:17
other issues01:30:19
how to write what I need not just01:30:26
cool now look how to return it here01:30:42
this is how you can write01:30:44
[music]01:30:49
like keyword boom boom boom01:30:54
percentage with percentage yes we will return everything01:31:07
lines that have c in our case01:31:10
these are words and c we can write like this01:31:17
yes yes you can start anywhere01:31:20
write it like this, it will mean everything01:31:23
what starts with s we can write here01:31:27
so it will actually be in fact01:31:34
equivalently equals01:31:36
in general it depends on the optimizer as01:31:38
he can do it and we can write01:31:41
of course we can write like this01:31:43
there is generally a percentage of sbc and a percentage of01:31:50
in fact, percentages of what is practically01:31:52
in all databases there is in the standard there is also01:31:55
I think underscore is one of any01:31:59
symbol01:32:00
are there some other type of brackets there?01:32:05
like the fighters are any for bc01:32:09
parentheses with negation01:32:11
we are like any unusual something like that but01:32:14
this is not regex01:32:15
yes it’s not, well, I mean, look at it01:32:20
simplest hex and01:32:23
in fact riddex also exists but01:32:26
It's different on different Saturdays01:32:28
it is used, it is not standards but in principle01:32:31
there are options and even use it, but you01:32:35
must understand that look what's here01:32:38
important to understand01:32:39
well it’s too early to say but look01:32:43
so that such a filter01:32:48
you probably need to do it01:32:52
view the entire sign as if we didn't01:32:55
tried to give and especially if like this01:32:57
yes, this is the filter we are talking about01:33:03
Nikolay said basically an optimizer01:33:06
must understand that if he has01:33:08
Yandex ps assorted, that is, he has01:33:11
the value of the name it stores is sorted in01:33:14
ok initially date he can immediately01:33:18
we can find the letter later, they are here01:33:23
no she lived01:33:25
find him running while he's there01:33:28
until he reaches the date there and then01:33:32
get out because it’s like it’s further01:33:34
there's definitely nothing to start with01:33:40
special operator like these are the simplest01:33:46
or xp that's the last thing left come on01:33:55
sort the case later if we are looking for more01:34:07
imagine imagine as if01:34:10
you would write a comparator you have two01:34:13
object when there you compare them01:34:15
and just this all the objects are obtained01:34:19
less than others, well, yes, look how01:34:38
sorting works, we have a lot of different ones there01:34:42
algorithms01:34:43
but in any of them there is an operation01:34:45
comparing one element to another01:34:48
elements correctly and how and when01:34:51
it will call the sort operation01:34:53
for your multitude which he will receive01:34:55
he will take your buy order after the fact and01:34:58
your executive will begin to compare01:35:01
all this for everyone roughly speaking there but for01:35:04
each element that it will be01:35:06
throw or something is wrong with them01:35:08
do it will call this case01:35:10
play off to get which one is bigger01:35:11
and sort them either left or right01:35:14
it was clearly explained, that is, everything01:35:17
rests on the sorting operation, that is01:35:20
there's no science here to know01:35:24
database you need to know01:35:28
What is the complexity of searching hashes, hash tables?01:35:32
difficulty search ok01:35:37
the sorting complexity is just logarithm n01:35:43
everything is almost everything yes it is still there01:35:50
just the complexity of line wire01:35:52
I pass the additional usual well, in general, everything is there01:35:55
there is bar 2 base operation put in hash01:35:57
or sort and there you are01:35:59
somehow everything lives between them most often01:36:01
accordingly you need complexity01:36:04
get the complexity out of the mess to build a hash01:36:06
it's hard to quote satire01:36:08
difficulty finding a toilet using a van01:36:10
there are no SEO guys on the list, but basic ones01:36:17
sheet algorithms are always on hash this is us01:36:19
Let's talk about optimization and what do we have?01:36:22
there is still the very last one left and01:36:24
the most straight brain01:36:25
a tearing thing in a tired class strongly01:36:33
tired01:36:34
cool now I'm still going to tire you family and01:36:39
then we'll take a break so look01:36:47
there is a last one about what I tell me01:36:49
told me but at least you should01:36:52
to hear about this is called this thing01:36:58
acne window functions wow wow wow yes no01:37:05
I could, but I read it, wow, you're in01:37:12
school that I dreamed of01:37:15
Already big they should start to nose01:37:19
ok look let's do that let's do that01:37:32
let's start with an example with our group de here01:37:34
we have a group go have our grades01:37:38
[music]01:37:39
boom boom 122 let's say 3 24 2601:37:53
why not why can't there be an assessment01:37:57
six and now we want01:38:04
pain is not possible, now is the time01:38:11
come up with something more interesting01:38:18
let's still have a date, that is01:38:24
let's say we got it there 0 1 0 1 this01:38:30
there 2 0 2 0 2 this is 0 3 0 3 this is also 0 1 001:38:40
1 well boxing is not important here we are01:38:46
now we want to withdraw01:38:48
grades in the order they were received01:38:55
let's say it will be quite simple01:38:58
via a buy order, yes, but we are still01:39:00
should we want to know if someone lets me01:39:07
know first received a rating is acceptable01:39:12
let's say which group passed the test first01:39:15
let me exhale on the matan there01:39:22
don't look we need to get that first01:39:29
but no, which group received it first01:39:36
let's just order and see how often01:39:39
I'll write a request and come up with something in blue01:39:42
by hon select now I eat like this01:39:47
ru bir umr01:39:59
steam quiet these are very difficult words I understand01:40:05
I'm honestly crushing the bird, what do you care?01:40:06
it was hard for you to understand that this is true01:40:08
hard actually seconds very easy01:40:10
parte shin bo and let's say group ID buy01:40:20
dt01:40:22
tun tun tun mark look now in short01:40:35
remember the concept of groups that we01:40:38
passed in rough01:40:39
remember Shin Bo's parties and does the same01:40:43
the most but his difference is that he is not01:40:47
collapses these groups01:40:49
he kind of does this this this this01:40:52
the group is different from the window it makes a window01:40:55
and in our case the window is this one01:40:58
line and window this is this line and with01:41:05
the same group and then we're in01:41:09
within the group we begin to sort by01:41:13
date and within this sorting01:41:17
apply a function uniformly which01:41:20
must be in parentheses and returned01:41:24
and in fact we are returning it here01:41:27
rough we supply here one here01:41:30
one two and three01:41:34
but in this case we use lines as groups01:41:38
rude they turned me down01:41:39
and we can actually do all these fields01:41:42
return the group get out of here mark from here and01:41:48
dt bomb and then we will return all these01:41:52
four lines no order not mine01:41:57
order when we don't ask for order01:41:59
order we don't get we just here01:42:02
here let's call this column with01:42:04
s and here she will be01:42:12
died yes that's the key word01:42:14
overpair silence buy order buy the all01:42:17
keywords no see parte shin bo01:42:33
do you think this is equivalent01:42:35
rudely in which they could write here01:42:39
yes, but you can’t write parties in here01:42:41
buy and there you can’t write rudely01:42:43
that's how they came up with the baader buy order01:42:46
they said that you can also call it well01:42:48
not consistent and guys and now we01:42:50
live with it somehow accordingly01:42:57
thus introducing the concept of a window01:43:02
a window differs from a group in that it01:43:06
the window does not minimize the entire group it01:43:09
Just01:43:10
we are in this we are within this window01:43:13
we sort and do something before actually01:43:15
in fact, we can be here, well, we can be here01:43:18
different functions exactly beer the simplest01:43:22
I don't know if there is a piercing or01:43:26
there look at the next line in01:43:29
window there are some really complicated things01:43:33
In fact, you can read about window functions01:43:35
if you're interested, but what's important here?01:43:38
look what's important is what's in this over clown01:43:41
in this over expression you are here01:43:44
after this function it is obligatory and01:43:47
expression is an order buy the parties in01:43:49
buy is not necessary if I have lots of tires01:43:51
because I’ll skip it here, it will be considered that01:43:54
I have all this one window and I’m starting01:43:58
sort by date and put them from in01:44:01
orders give this that is, this is here01:44:03
there will be one it will be 201:44:05
it will be 3 it will be 4 roughly speaking01:44:08
if you want to sort students01:44:11
according to their average assessment, that is, they did not name01:44:15
just sort and just even01:44:21
I don’t know what place I took back there01:44:26
there's some kind of average score there01:44:29
quarter there I don’t know if there is some kind of session01:44:32
then this throw set is just what you need01:44:34
need to01:44:39
you won't get a number but you won't get it01:44:44
what line do you have, is it 2 or 3 or there01:44:48
5 well, you'll just get a list01:44:52
sorted and here and here and here01:44:55
here you can write01:44:56
where is my rubber band and in this one too01:45:01
fill look here boom boom boom boom01:45:04
boom I can write 1 here and look01:45:07
I can write here01:45:09
there is no difference in the fact that they fold01:45:11
lines with rough01:45:12
known write in c equals 2 well c01:45:21
rough I mean the difference from rough so01:45:26
it probably won't work but01:45:27
the example is similar yes I made it up01:45:33
this doesn't exist it's just a month and01:45:37
day of the month is clear example of such clones01:45:46
function up01:45:52
here's a good question in this case01:45:57
let's say roland barn will operate01:46:00
let's say it says don't start here01:46:03
0202 yes and we just he took the number01:46:08
act like he would do 123401:46:13
that is, it will increase not the same but01:46:17
there is another01:46:20
horse function that will count them01:46:22
identical01:46:23
that is, roughly speaking, it’s like what is this01:46:25
you in sports if two people don’t know01:46:29
got the same result then01:46:31
in some sports they occupy the same position01:46:33
they share the first place, let’s say I don’t know in01:46:36
swimming is possible there if they can’t01:46:38
determine somewhere in some place they are all01:46:41
anyway there is some additional01:46:42
indicators one of them becomes01:46:44
first is second second even if not01:46:46
divided plus then and there are great difficulties01:46:49
after that, yes, if you have two01:46:51
people took first place, that is01:46:54
there is no silver medal and not always01:46:58
sometimes it exists and there are 4 winners01:47:00
and sometimes you might have something like this01:47:03
two people shared first place01:47:05
silver disappears there is only bronze01:47:07
Well, that is, in different sports it is01:47:09
solved differently somewhere they don’t let through01:47:12
this is a place where they don’t seem to be greedy01:47:14
they distribute and in the window functions there is everything01:47:17
implementation of such functions when you01:47:19
you have to behave one way or another01:47:22
question another question about verde indicate that01:47:30
we have a further window and that’s not all yet01:47:36
before I remembered some cool things but01:47:42
ciklum the match is simple, that is, here you are01:47:45
I wish I could tell you everything right now, it’s all01:47:47
will know nothing more01:47:49
Well, you can check there a little and it’s there01:47:52
another type of operation that we are not talking about01:47:54
we talked about operations on sets01:48:01
but you all know they are the simplest ones01:48:05
they are definitely class yes yes but repetition01:48:13
mother of learning01:48:14
therefore we repeat it means both him and him01:48:19
not so yes there is more except01:48:32
sometimes called minus there is also the most01:48:38
difficult word to spell inter ct01:48:45
what's interesting here but we're next01:48:50
Let's look at it once, okay, or now01:48:57
let's now we have two sets01:49:02
11 and 21 we make you new out of them01:49:15
that they will come back, there are so many of them01:49:22
but I mean the sign we have is nowhere01:49:24
this is not a set of correct before it is impossible01:49:25
call it a set, it’s kind of like there01:49:28
the cortege is actually a sign, that's why01:49:30
tables are not a lot but01:49:35
the result of the union operation is01:49:38
a bunch of01:49:39
so there will be no intersecting01:49:42
12 elements are correct, exactly the same in01:49:48
except yes that is all tribes01:49:50
happy one of 2 you read when you01:49:53
read 2 1 of 11 you will get that well01:49:58
let's say if we are here to these two01:50:00
we won't get anything with multitudes, but we01:50:06
we get it as if it’s empty01:50:11
that's it, intersect will return it to us01:50:16
we are all one01:50:20
and there are still not sure that in all01:50:24
implementation is worse than the operation, he has zero01:50:30
union all she seems to be saying simply01:50:33
add two sets01:50:35
that is, roughly speaking, or rather 1121 that is01:50:40
just do the concatenation without this01:50:42
without this muto there is a shadow out of many01:50:50
yes of course watch it this is important01:50:54
good question, see operations with01:50:57
many acts seen before him too01:51:04
got high a b c and d01:51:11
that is, if we do union I get no01:51:18
we do it in union here it is done on 12 and01:51:20
we need to get over with intelligence then01:51:24
there is, roughly speaking, let's say it01:51:25
returns us select 1 and these select 201:51:30
it’s clear, but no, put it like that01:51:39
so cunning he addressed these fields there01:51:41
you are asking about the old answer in this01:51:44
case, now we have something left01:51:48
after subtracting 1 there would be one yes you are great01:51:54
but we went through it, I think I can do it again01:51:56
look Igor help your neighbor01:52:05
good words, can you help these guys with anything?01:52:09
union at you is a little different what01:52:13
will return union for these two tables 1201:52:18
June on01:52:20
Igor don't you understand yes yes in the middle charge01:52:32
just like intonation just a plus sign bambi01:52:35
everything is wrong and I can’t do it all yes01:52:47
let's sawfly so let's let's01:52:51
let's do it this way, I'll invent it01:52:54
requests you will write them on this is super01:52:57
board and then other people will come01:52:59
come up with requests, we will write them on01:53:01
this is a super blackboard01:53:02
who wants to be first oh my god how much01:53:06
hands like, well, you were probably third01:53:09
was the first listen out01:53:12
I'll come up with an easy one for you first01:53:14
I figured it out now you'll start there what's my name01:53:18
Arkady we have a student sign we01:53:21
we want to know how many entries there are in it01:53:30
come on, are you going to knock now, no?01:53:41
it started you see01:53:48
yes yes at the same time I learned to write everything on this01:53:52
super blackboard01:53:53
then you will write in your resume who wrote it01:53:55
cive01:53:59
so look at the first rule we write01:54:01
we try to write requests out of line yes01:54:06
no way from this in one line select and01:54:08
went to select from the rough oldboy then01:54:12
there is like this yes under under the selector it is not01:54:17
under this photo on the right yeah I want to know what01:54:25
do you know the number of entries in the table?01:54:28
students, well, I just want to know01:54:30
number of students but you can go01:54:42
nickname let's write to please whoever yes yes yes01:54:46
look pierced write something01:54:48
option that is, I open an account01:54:54
an asterisk and you can write from01:54:57
acceptable di yes the same would be with01:55:00
he just wrote an opening parenthesis01:55:02
asterisk or the same thing could have happened01:55:05
write count opening parenthesis one yes01:55:08
just look there is a function01:55:11
account what's the difference if I write01:55:15
just took it away from you to break it01:55:19
let's say the account is not the version01:55:27
count let's say 1 than the difference between these two01:55:33
calculations but you knew they were great01:55:39
just smart yes yes everything is correct01:55:43
look at the count one as if there is always one01:55:46
not to us that is to he counts the quantity01:55:48
no cash lines who is the correct ID person01:55:57
most likely it can’t be on y too01:55:59
so these are equivalent entries01:56:01
but if you write account and name to01:56:09
it will actually call it01:56:11
will mean the quantity is not on new ones01:56:14
names on the sign Strelnya of course sooner01:56:16
in total they are all there no cash it will be01:56:18
the same but there is and can be a difference01:56:20
so come out there whoever is Lyokha01:56:24
next let's continue scout01:56:27
exercise and of course basti01:56:30
it's good to be afraid01:56:34
so I just want to know the quantity01:56:40
number of students with different names01:56:49
students with different names01:57:01
That's right, if you don't know, write select under01:57:04
write to him frome maybe an idea will come01:57:09
count one hundred percent quantity too01:57:12
will be there01:57:15
exactly yes, with different names is acceptable01:57:45
Not01:57:47
and this too, come on, write an asterisk there01:57:57
units what will it mean if01:58:01
let's say he writes there now or01:58:03
one or an asterisk, how much will it be?01:58:07
groups how many different names the account will return01:58:13
we just have the number of these different names and01:58:16
I asked for the number of different names not01:58:23
just that Sergeev 5 Alekseev 5 I don’t know01:58:27
there is slav 2 before and I want to know how much01:58:30
look here there are two different names01:58:39
option you need to either just wrap it in01:58:42
upon request or I will show you another one later01:58:48
shorter version don't bother me01:58:51
first our task is to teach everyone no01:58:59
wait no don't look here you are where is that01:59:02
here you can already look we are now in01:59:04
they will look up if you are now01:59:05
just return the name from this selecta01:59:10
you will only receive unique names for you01:59:15
after that you need to count them like this01:59:17
do wrap another select01:59:24
just erase it in the sequel01:59:30
what he wrote there somehow, his name is Arkady01:59:44
yes well done right yes yes at least something02:00:00
one move, even if we write an asterisk02:00:02
from must be written and yes02:00:06
distribute this time all the smoke will write to them than02:00:08
yes, that's it, I don't know about there, I don't know about there02:00:12
basically, that's okay, that's all02:00:18
this is how it will work, it’s clear which is02:00:21
there is an easy way for us to write like this02:00:53
I didn't tell you that, no that's not it02:00:56
said that action commands to write to you02:01:00
didn't say that special said that02:01:02
call you later and ask whatever02:01:04
said clearly, that is, in the county there is02:01:14
Here’s a feature you can write distinct not02:01:17
to account listings02:01:19
this is unique to the type number of different02:01:23
names, I told you about another me02:01:27
I'm telling you that in principle there is02:01:29
the word distinct can be written like this02:01:33
so select distinct02:01:48
student yes yes that's the key word02:01:53
distinct is actually practically02:01:57
the same thing that I just wrote through rude02:02:00
that is, this request will simply return to us02:02:03
unique and the number of names and even that02:02:08
it’s just easy to immediately count everything who02:02:12
ready to be next come here02:02:17
we'll come up with something for you02:02:30
so let's assume that we have02:02:35
sign sign with02:02:44
student go, mark, I want you02:02:53
calculated the average score for each student02:03:04
screams you find yourself02:03:07
select starts correctly let's call this02:03:11
sign using mark to give and say02:03:21
a little more space for02:03:23
thoughts on the front and the select type is02:03:30
very simple very simple until the end02:03:35
I can do this chrome after selecta myself02:03:43
always after select before02:03:47
he was asked for the average grade of the students02:03:50
find yes yes yes yes that is it's easy02:03:59
Petrov received such a statement there02:04:02
243 there02:04:12
close yes, practically, well, it’s still possible here02:04:16
display only student ID to understand02:04:18
what the student got is just yours02:04:20
option with this will be your request will be returned02:04:23
I'm 1234 in short absolutely some02:04:29
incomprehensible02:04:30
yes who is ready to be out next02:04:43
I want to know, don’t erase, I want to know night02:04:53
I'll tell you nothing clicks at all02:04:58
I want to know and I also need to be okay I want02:05:04
find out the top, well, I want to know the 3 coolest02:05:12
students by GPA02:05:20
I breathe select written from written rude02:05:23
it is written what to enter before smal daoud or02:05:30
fuel limit what to write exactly come on02:05:42
what to do I didn't just how and about02:05:49
distinct why tell everything I will02:05:51
ask you'll see surprised buy order like that02:06:08
no no from little 402:06:13
washing, washing and rubbing02:06:16
erase look so what we got now02:06:20
we just02:06:24
descending order of what I didn't actually torture02:06:27
what no disk no first fields then what02:06:30
so no no see it turns out wrong02:06:35
bad, by the way, this has never happened at the board02:06:38
was not the first time actually and this02:06:44
won't work well because because02:06:49
that you didn't name your column at all02:06:51
beat you very much and what to call02:06:54
now we have what to call yes there with because02:06:59
what to call from mac in principle to do this02:07:01
everything has grown together with m then word rbm does02:07:12
before02:07:20
and here it is given to write02:07:25
the limit there is 10, yes02:07:31
inside let's say so look there is02:07:35
operation limit or you told the server02:07:39
she's the top in regular databases she's spelled02:07:43
the latest here is the limit sometimes02:07:45
you can tell microsoft they are special02:07:48
they write here the 3do top it’s the same02:07:56
The best thing is that the guys just don’t want the limit02:07:59
repeat themselves and want to be unique02:08:01
that's why the perries come up with the same thing02:08:03
it's not up to the piano standard as far as02:08:05
I understand can be fixed in general02:08:08
this limits the number of entries to02:08:11
that is02:08:12
Igor calculated the average score for us02:08:18
Ruslana chose the leaders of the drive, he started it02:08:23
the biggest ones and left only of them02:08:26
three the only thing here is a subtle point02:08:30
and I really don't know how he is02:08:33
solved with a limit, let's say we have02:08:35
excellent students you have groups of people02:08:37
who have an average score of 50, that's me02:08:44
such and let’s say there are four such people02:08:48
imagine how it will be how it will be for them02:08:52
it would be a shame for the fourth one02:08:53
award 3 as if he is handsome too02:08:56
but in fact up to 0 and God bless him even02:08:59
one of them is 50 and all the others are there02:09:03
49 and we take it off in general from such02:09:07
here is the case, yes, I know for the top02:09:11
there is such a design called02:09:13
type of visa tires is called and it's like02:09:19
will return not the top 3 but, as it were, three02:09:26
and the last ponytail looks like it has swords, yes02:09:30
that is, it doesn’t seem like anything02:09:33
there are different ways to do this, let's do it02:09:39
look, let's make this trick02:09:41
then we will now call another person02:09:44
who now wants to go to our02:09:50
look at the board, let's do the same 3 same02:09:57
cool only through these through legal ones02:10:00
functions smell well to you anyway02:10:07
you need to write select here02:10:11
sure select02:10:14
this is what we will have in frame and from02:10:21
and then I write to you VR this is what I want02:10:23
for it to be like this02:10:24
m less than three let's say y no actually02:10:30
actually not 3 but 3 is not enough 4 I want the first02:10:36
three, yes, you know such tests02:10:41
when there will be something missing02:10:43
and you have to how would he do yes yes yes02:10:48
like this is where you need to paste02:10:50
I tell Arman what to install02:10:52
writes something through a legitimate function, well02:10:57
Well, let's say Ron Bard02:11:03
well exactly the number of lines02:11:05
let's say the anger rune is granted bere bere02:11:11
parentheses are a type of function, yes02:11:14
let's clean it all up this is this02:11:18
we'll clean everything up so you have room02:11:24
[music]02:11:26
[laughter]02:11:30
don't look it's spelled the crown amber later02:11:51
always written over exactly then02:11:54
the bracket opens and the magic begins02:11:57
in which there are 2 2 of these things lots of tires02:12:01
buy and buy order we need to place first02:12:09
3 highest average students02:12:15
point02:12:17
1 yeah it started, there’s no place for you there02:12:26
enough for this okay so come on come on02:12:33
We'll erase this so it doesn't bother you02:12:36
then more02:12:41
no look sculpting me so funny02:12:46
call it column02:12:47
as it was called games for you no never02:12:55
completed the request you and you to the hall before02:13:08
this is all a bracket close the field call us02:13:15
name the field as needed, name the field no02:13:21
the field needs to be called and the same filters for them02:13:25
Anapa from below you see in n4 everything is not like that02:13:32
no wait, that's it, in short, yes, my God02:13:42
belly now look at the magic of the veteran02:13:46
erased let's do it like this until op op02:14:00
s m everything like this when you wanted it there02:14:04
so the guys understood what happened02:14:07
realized black a lot, turn on already02:14:12
Arman thank you then you will cut this one out02:14:16
block from the video and I don’t know yes yes yes a02:14:26
there was some kind of agreement, everyone understood02:14:30
I just realized we launched the window function02:14:42
who knows how to row set just knows how to02:14:47
within the window and sorting assign to us02:14:51
line number 1 2 3 4 5 line line02:14:56
these are sorted by which we received02:15:01
from this on request and here in yes everything02:15:05
and accordingly we received this row02:15:07
number actually actually if02:15:09
be frank and honest02:15:10
this query will not work because02:15:16
because at this stage the columns are n02:15:22
will not exist yet02:15:24
Yes, and in fact, this is still needed02:15:30
every 15 select wrap here02:15:34
write select m there from this one02:15:38
little thing and then you can filter02:15:39
but I understand the idea, look at Sparta02:15:48
tires are acceptable02:15:49
come out let's say we want let's say we want02:16:00
chat wait wait then don't come out here02:16:10
it's nothing written02:16:13
it's written the name of this one under02:16:16
selecta sd it's called d why but you can02:16:19
let's name its date, let's say02:16:23
so look Arkady and please return it02:16:30
let's say we still have a group there02:16:37
can you make us return 302:16:40
not the coolest guys based on GPA02:16:45
guys are just people by GPA02:16:47
group to for each group .02:16:50
the guys then act like all sorts of sexists02:16:54
they shut up, well, yes, through the Shengi parties02:17:00
you will need to sharpen it a little02:17:01
most likely the internal request is clear02:17:05
idea we want 3 coolest guys in02:17:09
group to give them an increased02:17:10
scholarship is the top three in each group02:17:17
not just three in general at the university02:17:20
let's say in the entire database of three everyone lies and02:17:28
well, that’s okay, okay, I accept it02:17:36
your challenge is going to be written off02:17:41
parties in buy group dim you need02:17:46
return him in a group where you didn’t return him02:17:49
from the previous internal selecta I you02:17:53
don’t believe me I can’t talk about anything else02:17:56
you have a call in the inner select and not02:18:00
returns as a group02:18:08
let's say yes02:18:17
and it won't work until because02:18:24
rough no group de02:18:25
and you can't return this column yeah02:18:40
so nothing will change right well02:18:45
you can't write like that02:18:46
because this will be the average rating of everyone02:18:50
students in the group, yes, but we wanted to return02:18:54
3 best students in each group02:18:59
[music]02:19:01
yes yes yes and it will actually work02:19:12
It’s clear that we still have to be there02:19:14
select some fields, well, in principle, yes02:19:16
it will work well here it’s supposed to be02:19:19
understand that this is this, this is this, this is how this is02:19:21
you need to read here we wrapped up here02:19:29
here well how much dinned we have up to02:19:44
within each group within each02:19:47
groups in the sense of a student group02:19:50
we will have our own n yes we will have there 12302:19:54
for how many people group here02:19:58
now Igor of course yes come on please02:20:05
come out and do it so that if dude02:20:11
C student, we never got him back02:20:22
[laughter]02:20:30
you can even do that with your fingers not only02:20:33
chalk is not in the game, the mark is only on the actual02:20:46
in fact it’s not possible yet because select02:20:49
will only work after peeling02:20:54
Handsome02:20:58
above, well, here, too, the C students are so-so02:21:02
as if more than four want to write well02:21:10
ok well there is also in g that's right02:21:12
that is, 31 will be 32, yeah, well02:21:16
in short, more than four will be a mink02:21:18
yes you can write more or equal02:21:21
this is normal too, let’s just say no02:21:25
principle al valida having worked02:21:29
it turns out this is a useful thing02:21:34
there is accordingly here we wrote 302:21:38
tried to return the 3 strongest02:21:41
students but who have at least a score02:21:45
four02:21:46
so let's give them something02:21:50
suggest another problem, we’ll come up with a great idea02:21:55
Now we’ll come up with a join and write something like02:21:58
we'll deliver02:22:03
[music]02:22:06
Sanya now we are someone so who are we 302:22:14
row wants to leave02:22:15
blackboard come on you're cool so let's do it02:22:21
Let's come up with a problem: what's the name Misha?02:22:26
no one wants music mesh I need it02:22:29
come up with it, okay, let's return the list02:22:34
all students with the group name in02:22:38
whom they learn I substitute everyone like this02:22:45
specially rubbed include so select02:23:00
water plastic yes yes yes02:23:19
Well, let's say Misha will figure out how it will be02:23:22
to be called that is, the name is roughly02:23:24
just a group up or large you can too02:23:29
do it just fine with your finger02:23:32
we can do large ones excellently who submitted hb chrome02:23:41
[music]02:23:44
need to be returned in one list02:23:47
student's name and group name02:23:50
learn can't be worked down in02:23:54
we will not consider such a group to have02:23:57
for now let's start with the fact that he doesn't02:24:00
he studies fundamentally well02:24:02
several groups until students can02:24:05
study in several groups said so02:24:13
let's try to imagine what it would be like for you02:24:16
we have one this student plate02:24:21
we have a sign with students up in it02:24:28
there is a dipole group there is a group sign02:24:35
here yes means here there is on them and here02:24:39
there are large before we are in general there are02:24:55
there are large ones02:25:00
and there is an idea for this group to02:25:07
accordingly, they are connected through this02:25:11
the field after frobo first write chrome02:25:24
where do we get it from?02:25:40
yes everything is correct so far everyone02:25:50
students with their names02:25:53
well it depends on whether it happens02:25:58
students without groups you can be a student02:26:02
Biesbruck University we will consider02:26:05
what doesn't happen has begun02:26:10
because then when the next person02:26:13
will come and think so it happens02:26:16
students who do not have a group02:26:21
that means the columns in this one are large02:26:23
some are small, okay, okay, I'll be there02:26:28
provide this in your code and then02:26:29
Damn Igor, I just wanted it02:26:31
write as if why can’t it be a bluff02:26:33
write it like this, this is roughly how it happens02:26:36
but it already returns the same thing, like those02:26:39
same data02:26:40
2 2 groups it is clearly written there I thought02:26:50
you need to eat now02:26:55
name of the tables you will be with02:26:57
jones yeah right now how do you get them02:27:08
you will connect it will fit into yes yes02:27:13
it's spelled he he02:27:28
personally and now we will provide02:27:31
we think that the students' nameplate contains02:27:33
ID field02:27:34
well, the same group day and this request02:27:36
won't work then look02:27:39
in short, look how he did he didn't02:27:43
used aliases he just said02:27:44
group go equals go and it will be02:27:46
work if you have all the fields it02:27:49
unique date named there is you on02:27:51
the payday game only intersects with you02:27:53
sign02:27:54
1 and Aide of Tukov tablets 1 then there he is02:27:57
will figure it out, but if not yes yes yes yes02:28:02
you are there, like, well, yes, with g there, yes02:28:19
ok, well done, so who else?02:28:24
wants to let your neighbor in the back02:28:29
don't be afraid, as everyone calls him, come out, come on02:28:39
we will try to leave only those02:28:44
students02:28:46
a group called begins with02:28:49
letters a whose group begins with a02:29:06
group of which groups are possible and in full02:29:18
there's really nothing wrong with miles02:29:27
It's not so easy to put it all starts with02:29:36
letters yes you can write it like that look02:29:45
she's right in02:29:48
well done thank you not so much02:29:51
It's scary, look first of all02:29:53
made by Ira02:29:56
she didn't use an alias02:30:00
right away by the name of the sign, so too02:30:02
you can actually and the sheet like this02:30:10
also possible secondly what did she do02:30:12
I wrote to energy not through and it’s possible02:30:16
was to write let's say it would be02:30:19
absolutely in this case the same through02:30:23
yes, that is, if you change these two02:30:26
words would do nothing in this case02:30:28
changed so who wants more you would02:30:38
let's erase it all already02:30:47
look I want it back I have it02:30:54
sign02:30:56
students sign students and eat02:31:01
rating plate magician style no well here02:31:09
it’s clear here and here and in inside02:31:13
there are marks here I want everyone back02:31:19
students who have not yet received grades02:31:22
no at all I want everyone back02:31:27
students who did not receive grades02:31:31
I want to return the students ID02:31:34
kotova which have no ratings yet02:31:52
I don’t know, you can look at it differently02:31:55
start max dividend won't work02:32:13
so wait, let's not think about what02:32:18
then join is great but not John is like that to02:32:31
join this than with students is acceptable02:32:43
no so what02:32:54
no metro you can eat but from the outside02:32:58
let's go02:32:59
why won't john start?02:33:01
Let's figure it out, let's go and what if02:33:12
it turns out the students will be here come on02:33:23
it just won't work yet02:33:25
because he doesn't have you02:34:04
fire and now you only see this02:34:07
everyone understood the field02:34:13
everyone understood exactly what happened02:34:16
was give among02:34:22
so look there are three outer join a fool02:34:29
left and right right and then you say02:34:33
what are you leaving behind02:34:36
the right sign is inviolable02:34:40
take all the lines from the right plate and02:34:42
trying to reach her02:34:45
attach a left sign if you are left02:34:48
you can’t find the sign, you write here02:34:52
if he wrote here as a student and02:34:55
because mari you are looking for all the students02:34:57
who have no grades, that is, without need02:35:01
a student sign is required, that is,02:35:03
for text for those lines like once upon a time02:35:06
I didn’t find the rating here you are displaying and knew02:35:12
this is how life is like, he's the best guy02:35:15
cool request02:35:18
You can also write it like this02:35:31
there02:35:33
selecta go02:35:37
Well, of course, of course, a person who02:35:41
I wrote glass for a long time, I would write it through the lion02:35:44
g02:35:45
because it's a tradition that02:35:49
Almost no one writes Wright, that is02:35:52
write down this is pure paradise joy02:35:56
well, that’s how it is, but you’re right02:35:59
wrote well done where am I02:36:08
not in was select shame02:36:24
Mark class seen like this I can’t02:36:28
student getting a02:36:43
[laughter]02:36:45
By the way, inertia seems to me to be simple02:36:54
amazingly clear what I wanted to say02:37:03
look I'm solving the same thing02:37:06
wrote via join and nights02:37:10
through in one not in could you still02:37:14
write like this 90 like this no like no02:37:28
[music]02:37:31
existential so well then select or else02:37:44
Cupertino people02:37:46
where there is no so before I will call02:37:51
with there is a mark student if they led02:38:12
screwed up it should work sense02:38:16
is that I use02:38:18
the design is not existential and I say that02:38:22
please give me back those students for02:38:24
which there are no rows with the same02:38:28
shame like the ID on my sign in March02:38:33
down and actually me this one02:38:35
column feeling is important I can return it02:38:37
let's just say one because not02:38:40
basically I'm actually here02:38:42
I work within the existential mode02:38:51
until you just don’t exist and that’s for real02:38:55
in fact, the request is again correlated if you02:38:58
understood, yes, that is, I’m for him02:39:00
correlates with this condition02:39:02
natusya how to say how to02:39:05
said please for every line02:39:08
from here check if it exists here and02:39:11
this is not a quick request but in principle02:39:15
working loan square in the simplest02:39:20
implementation further then if the optimizer02:39:22
he will understand that he is like that but they were like that02:39:27
we are trying to rebuild the request02:39:29
let's rebuild through yours there02:39:32
Lev Jonchik for Joni two sets02:39:34
let's say behind the ent by everything so that more02:39:44
I wanted to ask02:39:45
let's do this thing for the last time we02:39:52
today we will do it and go our separate ways02:39:56
home02:39:59
who wants it, let's just give it please02:40:02
look we have 2 you were02:40:10
and with speakers02:40:14
a and b you were b rock smart a and b02:40:26
problem I want to compare what these signs are02:40:33
contain the same values02:40:40
well, whatever it is, it’s really simple02:40:43
I want to understand02:40:44
the same meanings in these plates or02:40:47
no, write to someone with ideas somehow02:40:57
first of all I have two questions02:41:02
signs in each of them two fields I want02:41:05
Write a request like this to compare what02:41:07
these plates have the same meaning or02:41:14
write ready come out come on come out and02:41:19
some name forgot 7 well done come on02:41:22
come out02:41:23
we have Arkady there is Arseny words02:41:27
prem ke cool for everything at the factory02:41:34
his name that the battle does not call arkash02:41:36
you need it, you can even be a writer02:41:40
special marker02:41:42
you can say first and act union02:41:52
equal to the intersection let's do it anyway02:42:01
zero so politics with you such a site02:42:11
that's right, well done, let's start, we'll rule02:42:13
select from the selected wait let's go to02:42:25
except or minus can be written02:42:27
let's start all the lectures over again for now02:42:30
we write in the column on the right in bags02:42:34
Stalin didn’t look at the expression, where are you?02:42:36
there was, do you know, the fight before the prom02:42:54
where come from and don’t call me names, well that’s it02:43:06
so come on come on now we're selecting out02:43:17
columns from b let them write okay02:43:36
realized that he had struck somewhere else, so02:43:41
now all is well and cassettes or minus02:43:46
if you want to learn let's say from02:43:48
set set well let's say let's say02:43:57
wrote tx m yes here no write02:43:59
except that is, there will be only sound in02:44:05
end not exit x and i cassettes02:44:12
you collected wrote as an exception exactly02:44:15
oh my god you are correcting us here as a test02:44:17
the word xcx and still not, so what is it02:44:23
let's look let's counterexample 1202:44:28
1302:44:30
he doesn't even just like that cm or 12 boom boom02:44:34
boom Boom Boom02:44:35
and here 12 13 everything is yours for just returning02:44:46
no, he will return to himself, they say unscientifically02:44:48
question yes he will return it just empty02:44:53
empty denomination check let's junior02:45:04
let's say we write here, let's say02:45:06
let's just write uni here02:45:15
how simpler it is, everyone is equal and work well02:45:29
because it doesn't work until the end02:45:34
it works, I’ll give you an example, it will say02:45:37
that it won't work as much02:45:38
will add a specific task we have02:45:44
two signs you need to make sure that they02:45:47
the same lines and what not he writes02:46:01
completely different things but really02:46:03
I think the same thing at least a little bit02:46:10
one place you had to think gas02:46:14
I say in one place it was necessary02:46:16
think 3 and forgot about it, it will be like that02:46:22
work requests why if02:46:26
unique and another once yes02:46:39
right, that is, roughly speaking, like this02:46:41
example from here02:46:46
before 12 12 everyone understands that these are different02:46:52
signs but it's empty and the frames are correct02:46:59
not ours our request will return yes from us02:47:03
will return return empty we will count02:47:05
that the request on the sign is the same02:47:08
they are different and the same will happen no02:47:22
look after any except and after02:47:24
any interception from and in short not02:47:40
fundamentally once you have used02:47:41
any operation with a set except02:47:44
union intercept you have lost what you have02:47:48
you have, in short, collect you moved from02:47:51
areas of strings to area set and all02:47:55
as if in this one we lost as if before02:47:59
count something02:48:01
or something will somehow turn out02:48:13
number of occurrences so be it02:48:18
work approximately yes yes so understood the idea02:48:23
that is, in fact, we look like02:48:26
husband, as it were, well, that is, this is one of02:48:28
one of the solutions and to the plate a.b.02:48:34
add a column02:48:39
c which will store the quantity a02:48:48
and b02:48:50
need number of pairs a and b02:48:53
Well, it’s not just unique, but it’s clear that02:48:56
for each pair for each unique02:48:58
couple and bada number of unique park02:49:00
I see, well, roughly speaking, right here02:49:06
here column c will be 1 a02:49:09
here it will be 22 before here and then if we02:49:19
we'll get a column like this and then when02:49:21
we will write just such a request02:49:24
no longer in two columns but in three then02:49:27
this will work before this it won't02:49:31
there is no simple way to work and02:49:35
in fact it is useful not only that02:49:37
there is such a way, it is most likely there02:49:39
will return more particles but imagine02:49:42
what kind of tables do you actually have instead of these?02:49:45
in fact there are some other select and and02:49:47
took the output and wrote some select there02:49:51
for 100 lines and then you took it and you think yes02:49:53
this is generally nonsense, I’ll write it down at three02:49:55
you know the lines, guess it from three notes once02:49:57
wrote in 3 notes wrote you'll make it up02:50:00
compare his character, well, you’re just like him02:50:02
just to compare something like this02:50:04
you can make an asterisk and check who02:50:16
By02:50:18
so not important let's say for example but how are you02:50:20
you will do this as you compare the column here02:50:22
here we compare the column with all02:50:24
column values would be yes but no but in02:50:32
in general, who is one of the ways here?02:50:33
right now the only thing we need02:50:35
we need to come up with this as a column with although02:50:38
I would like to write rude for one occasion02:50:46
you can't, okay, you can, rude, show me how02:50:50
show me, let's try, let's go out02:50:55
and until there is silence through the steam zones it will work out02:50:59
easier02:51:02
everything will work out for you and through the rough too we02:51:05
for example, the torso is just not just02:51:08
here here write how I did it myself and02:51:14
You fooled me, I think this is where select is02:51:16
and just here let’s say a, b and02:51:19
determine which column c is missing because02:51:28
that you are always in how much you02:51:45
write it on a piece of paper and then show it to me02:51:47
ok we'll see how it goes02:51:52
leave for a couple as if not even02:51:55
you write down what’s just like home for you02:52:00
write the assignment at home and then come back02:52:02
try me in the chat or chaise if not02:52:06
will allow you to spoil his paper must be done02:52:10
why won't it work without a unit?02:52:12
first you need to write often and go rudely02:52:15
constantly rude and then02:52:19
there was a front02:52:27
rude let's leave it you can but you need02:52:42
look you need to count the quantity02:52:44
such couples of such groups actually02:52:50
Actually, I just don’t know the account02:52:53
why is daddy units not counting in principle02:52:56
works within the group everything is like that02:52:59
hips here, but you can do it another way through02:53:05
ditch number through legal function yes so02:53:07
well, how would you be here, how would it be02:53:09
will work look he said that02:53:11
rude I would have reduced everything to groups but added02:53:16
how much extra is there for us?02:53:18
in fact, due to sss before, I only added02:53:22
Hello, did you realize how many such groups there are?02:53:25
I don’t know how many cardinals these are02:53:27
I don’t know how many such groups there are out there02:53:29
would like to compare these records later02:53:32
in three like this it will be possible02:53:33
compare it will work give or take02:53:35
same here is a question for today02:53:41
I have a couple of questions for you pir question02:53:44
how do you like it es que el is it normal02:53:48
wrong answer to so good02:53:52
fire should answer then how would I02:53:56
I'm happy and if not that's all for today02:54:01
I told you everything I wanted, thank you02:54:04
bigDescription:
Другие лекции курса: https://www.youtube.com/playlist?list=PLrCZzMib1e9reQb3ZXLWVaEu2CM3R54ho&playnext=1&index=1 Подробнее о курсе: https://polis.vk.company/social/after-login/?next=/curriculum/program/discipline/790/#auth Лекция Сергея Михалева по курсу «Использование баз данных» в рамках образовательного проекта Технополиса. Семейство функций JOIN и соединение таблиц. Агрегация: функции COUNT,MIN,MAX и др., GROUP BY и HAVING. UNION. Использование подзапросов. Понятие VIEW. Транзакции. Конкуренция, параллельность и согласованность. Взаимовлияние транзакций и проблемы lost update, dirty read, non-repeatable read и phantom read. Уровни изоляции ANSI/ISO. SET TRANSACTION ISOLATION LEVEL. Блокировки. Смотрите также: ► Курс "Использование баз данных (Технополис, весна 2017)" - https://www.youtube.com/playlist?list=PLrCZzMib1e9quWpe1VS-kpOsU6Cfj8Z0K ► Курс "Введение в Java (Технополис, весна 2019)" - https://www.youtube.com/playlist?list=PLrCZzMib1e9pz7f30YqoBLY0_AfiC36kM ___ ТЕХНОСТРИМ - образовательный канал для IT специалистов. ___ ПОДПИСЫВАЙСЯ, ЕСЛИ ТЕБЕ ИНТЕРЕСНО УЗНАТЬ: ✔ как наши преподаватели – топовые специалисты Mail.Ru Group руководят разработкой в таких проектах, как Почта, ВКонтакте, Облако, Maps.me, Одноклассники, и решают сложные задачи каждый день ✔ реальные примеры из практики с анализом их достоинств и недостатков ✔ современные технологии, которые применяются в проектах-лидера Рунета ✔ о митапах, мастер-классах, вебинарах и других мероприятиях, которые проводятся на базе вузов и Mail.Ru Group. Нажмите здесь для подписки ‣ https://www.youtube.com/TPMGTU?sub_confirmation=1 Все наши лекции проходят в ведущих вузах страны: МГУ, МГТУ, МФТИ, МИФИ, СПбПУ. ___ ТЫ СТУДЕНТ? Вступай в наши образовательные проекты и участвуй в чемпионатах. Лучшие студенты получают возможность стажировки в Mail.Ru Group. Отбор - каждые полгода! Технопарк при МГТУ им. Баумана ‣ https://park.vk.company/ Техносфера при МГУ им. Ломоносова ‣ https://sphere.vk.company/ Технотрек при МФТИ ‣ https://track.mail.ru Техноатом при МИФИ ‣ https://technoatom.mail.ru/ Технополис при СПбПУ ‣ https://polis.vk.company/ Чемпионаты для программистов ‣ https://cups.online/ Mail.Ru Group для образования ‣ https://vk.com/mrgforedu
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