SQL SELECT Statement Tutorial

Watson Tech World

Learn the basics of the SQL SELECT statement in this quick tutorial! We'll cover retrieving data from tables using simple examples. No database installation required! Practice along using the mycompiler.io link below. Plus, see the SELECT statement in action using a real MySQL database. Perfect for beginners! --- Code from the video: https://www.mycompiler.io/view/Jd9aaO6JUOx Run SQL code online free: https://www.mycompiler.io/new/sql --- Get my coloring book, Watson the Time-Travelling Dog 🐕🦖👇 https://watsoncoloringbooks.com/book1-locations/ --- Our website: https://watsontechworld.com --- 00:00 Intro and overview of tutorial 01:00 Teaching about SELECT statement in a document 02:20 Showing mycompiler.io with SQL next to spreadsheet 04:04 Creating the table and inserting data 04:50 Notes about SQL semicolons P1 05:15 Info about comments in SQL 05:57 Running first SELECT statement with * 06:35 More example SELECT commands P1 10:38 Notes about SQL semicolons P2 10:57 More example SELECT commands P2 12:07 SELECT commands in a MySQL database 14:22 Conclusion about SQL SELECT statement --- #SQL #SQLTutorial #MySQL #SQLSelect #LearnSQL #SQLForBeginners #SQLBasics #DatabaseTutorial #BeginnerSQL #database

Transcript

00:01Hi everyone, in this video I'm going to teach you about the SQL SELECT

00:05statement and I'm going to try to make this a simple tutorial but also very

00:11useful and it can be interactive for you. So I'll give you a link to where

00:16you can practice it by yourself and I'll try to make this a useful tutorial.

00:23Eventually I'm going to show you how to have some text and we can try out

00:29using the SELECT statement with a few few different lines and that doesn't

00:35require any installation of database and eventually I'll show you how to

00:40actually run it in a real database. I've made a temporary database or teaching

00:45database and we're going to be using this data for the tutorial and it's a pretty

00:54simple table. It's about salaries and I'll go over it in a bit. Okay, so let's get

01:01started. The SQL SELECT statement. What is it and how does it work? Okay, so SELECT is a

01:11way to retrieve or get data from a table in a database and a table in a database is

01:17kind of like a table in a spreadsheet. So it's kind of like this. Essentially we'll

01:22be getting data from a spreadsheet like this and yeah so it's like getting from a

01:31spreadsheet in Excel or Google Sheets etc. The basic form of a SELECT statement is

01:37something like SELECT some columns from some table where some filters. Here are a

01:46few examples. So SELECT star this means select all columns and salary is the

01:52salary table and for example let's say we want to get the name, career, and yearly

01:59salary from the salary table. That would be equivalent to name, career, and yearly

02:06salary. That would be the equivalent of getting all of this data and then we

02:10would ignore this data. That's what the SELECT statement would do. Okay, so I'm

02:14going to show you side-by-side with the data and doing some commands.

02:22Okay, so I tried to zoom in as much as I could to make this text as big as I could.

02:29On the left side here I have the spreadsheet and I'm actually blocking one

02:33of the columns to save space. We'll just deal with these columns and on the right

02:38side here I'm using a website called mycompiler.io and basically what this is a

02:47great site where you can basically run code online, different programming code and we're

02:54going to try with SQL. So you don't actually need to install any software. All you need

03:02to do is just go to this URL and this is going to be the default code but I'll give you a link to where

03:13you can copy all of my code and you can override the code and run it and although if you want you

03:22can follow along with the tutorial just copy all my code and you can follow it along. Okay, so the first

03:28things first is that before I show you about the SELECT statement first we have to actually create the

03:38table and we have to insert values so that means we have to fill up the table. I'm not going to teach

03:46you about this but you can just copy it and paste it and basically you can take it as as is

03:58and a second here

04:04okay so the first thing is all you need to do is you can just take this as given so you can copy and

04:10paste all this text this just fills up the table and nothing happens at first

04:16and you can actually run this code before we do anything you can run the code and you can run it

04:24with this just click on run and give me a moment here okay I have an actual I actually have a SELECT

04:34statement I'm going to rerun it okay so you should assuming that all of these are commented out you

04:40should see something that says execution completed and that just means basically nothing you don't see

04:46any actual output but there's no errors which is good and one important thing about SQL is that all

04:53the statements have to end with a semicolon so if you accidentally delete a semicolon or leave one out

05:00you might get an error and it might complain and refuse to work okay so again I'm going to assume that you

05:06already have this and I'm going to show you these these lines now so real quick so any line that has

05:16a dash dash like this those are comments and I this is also a comment which means the system will ignore

05:24it but you can delete all these lines if you want with the dash dash space those are just my commentaries

05:30but the ones that have the hash like this those are actual commands you can run if you remove the hash

05:38and I'll show you what I'm talking about so I just removed the hash for this and it actually ran this

05:43command but if I put the hash there again and rerun it you should get no output and then if I remove the

05:51hash for these other ones it's going to run the command okay so what this says select star

06:00from salary what this does is it selects all the columns and all the rows from the table called salary

06:12and the output is all of it and notice I'm not showing you the age group but it includes the age

06:18group so it shows the name career yearly salary gender age age group and all the different rows

06:24values so star means all columns but now let's say we don't want all the columns let's say we want

06:36and I'm going to comment this one out just to prevent having so much output let's say for example we want

06:43the name column okay so I just moved the spreadsheet again so it's easier to see now let's say we want

06:55just the name column and the career column and the yearly salary column from this and this is so select

07:06this column this column and this column we have commas in between and then the from we have to choose

07:13a table so the salary table which we defined earlier this I defined the salary table but you can copy all

07:20that code and what this is going to do is just give us the those three columns so notice here we just have

07:27name career yearly salary and I'll move this over here name career yearly salary we've got Brad

07:34who's a doctor has 150 000 per year sana as an idol and a singer has almost 1.5 million a year and so on

07:43and yeah so that basically got all of this data and it gave us three columns

07:54now let's try one more instead now let's do the same thing but instead just get females

08:02and I defined uh the gender column here with m being male and f is female and what this is saying

08:10here this this is basically the same command as above but now we added a where statement and where is a way

08:18to filter so instead of getting all of the rows where is a way to filter the rows so gender equals female

08:27that's a filter and let's run this so the first female is sana and then we have leia and then cheryl

08:42and julie we see here as sana leia cheryl julie and so on and that got just the females and notice that

08:50there's much fewer rows because the males were removed but now let's say we want to get all the males

08:56males instead of the females let's say let's get the males so the gender is uh is m and i'm going to

09:05comment this one out so if we want just the males we've got brad luke tony right here brad luke tony mike

09:14nick and so on and that's a way to filter by the males and now let's uh filter by the yearly salary

09:24so for example so for example let's say that we want people who have a salary of 150 000 or more per

09:34year for example leia is a chemical engineer nick we've got um sana brad but people who make less

09:42less than 100 000 per year tony mike pilar sarah so they're going to get filtered out and what this

09:51statement does this means greater than or equal to and if we had if we didn't have the equal that would

09:58mean strictly greater than 100 000 but this means greater than or 100 greater than or equal to 100 000

10:05and let's run this now so now we're just filtering by the yearly salary we're not filtering by gender

10:15and then we can see here we have brad who has 150 000 sana leia nick sonia and mary all of them have

10:26more than 150 000 and notice that there are none that have less than 100 000 so that's a good way to filter

10:33out and let's do another one here now i mentioned about semicolons technically sql statements can run

10:45over several lines one reason that they have semicolons is so the system knows that it's the end of the

10:51statement so we can actually run it uh for example here here what we're doing is we want basically the

11:00name column the career column and the yearly salary column from salary where the yearly salary is

11:06greater than 100 excuse me greater than or equal to 80 000 so for example uh luke will now be part of

11:16that previously he's less than 100 000 so he wasn't part of that but he will be part of this

11:22and also we can fill okay so what this is saying is we want all the males greater than or equal to 80 000

11:29so we have greater than or equal to 80 000 and then i added the and and means another filter so two filters

11:37and uh i'll show you the output here

11:42so get the name career yearly salary

11:45from this table salary where the yearly salary is greater than or equal to 80 000 and they're male

11:50okay so look we've got brad luke and nick all of these people have they're all male and they're all

11:59have a salary of 80 000 or more

12:06okay now what i want to show you is a real database instead of just this i'm going to show you a database

12:11um in mysql with the same data and showing you how to run it there

12:20okay so this is the same data

12:23and notice we have a salary a salary table and the salary table this is a mysql command that says

12:38tell me about the columns of this table and what i'm going to do is say select star

12:44from salary and what this does is this gives us the same data this is the name column career yearly

12:53salary gender age age group and that gives the same data and notice yeah sql is is really incredibly is

13:01amazing and uh you can see the benefits of sql over using a spreadsheet if you use it enough but

13:08uh it really is very very useful okay now let's say we want the name career and yearly salary

13:20from salary so this is the salary column excuse me the salary table so this is the name column

13:26career column yearly salary column and the salary table so notice here we have the name career yearly

13:34salary salary and so on and if we want to filter by for example and and real quick it is good practice

13:43to have these the sql keywords as all caps technically you don't need to have it all caps but it is good

13:54practice where gender equals female okay so this is um getting just the females and let's say for

14:04example we want the females and yearly salary greater than or equal to 100 000 so these are the females

14:17who make pretty good money at least 100 000. okay so the select statement is incredibly useful and i just

14:26showed you now in in a database an actual database in mysql and on this website in the website

14:31and i'm going to give you a link so you can copy all of this code and again as a reminder you can go

14:39to this website my compiler.io you can search for sql and you can run the code that i gave you and do it

14:48interactively okay i hope you enjoyed this video if you enjoyed it i'd appreciate it if you could subscribe

14:52to a follower of this channel and see you in the next one thank you

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