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So the next couple of videos are all about tables, which are the most important part of SQL.

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They are the true heart of using SQL.

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And in this first video, we'll start off by setting the stage or setting the table, if you will.

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Let me get away with that for how they work, what they are, and then we'll dive into data types next,

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and then we'll actually create tables and see the code that you use to create them.

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So let's get started.

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The first thing you should know is that a database is just a bunch of tables, so we've already created

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a couple of empty databases and deleted them as well.

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But what goes in them are just a bunch of tables.

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That's where the data is stored.

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As a short aside, this is in a relational database, so everything we're talking about that uses SQL,

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things like my SQL PostgreSQL, those are relational databases, and they use tables, they use tabular

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data, but not every single database in the world does, and we'll see some examples of those later

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on.

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This course is not about those types of databases, but it helps to kind of bring them in to show you

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some contrast to what you're learning.

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So we'll see that later on.

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Just a short caveat there.

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So tables hold the data.

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That's my definition.

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If you want the boring Wikipedia definition, it looks like this.

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Tables are a collection of related data held in a structured format within a database.

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Hopefully you're still awake after that.

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But let's take a quick example using cats.

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So we're going to model some cats data using a table.

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So let's take a quick look at the cat's table.

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Drumroll, please.

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Dumped it or dumb?

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I know.

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It's pretty hilarious.

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You're probably falling out of your chair.

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All right, so the real cats table, at least in this context, doesn't have an apostrophe.

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Look, something like this.

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And of course, there's a million different ways we could break down the data for a cat from modeling

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cats.

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In my case, I just went with name, breed and age so we could do plenty of other things, like location,

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gender is spayed, is neutered, that sort of thing.

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But just doing name, breed and age.

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So I've put a couple of cats in here.

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We've got Blue, who's a Scottish foaled, who's one year old.

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That's my cat.

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We've got Rocket, who is a Persian, who is three years old, totally made up Monty, who's a tabby

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who is ten years old.

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That is my childhood cat.

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He's still kicking and biting people.

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We've got Sam, who is a munchkin.

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If you don't know what that breed is, look them up.

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They're pretty hilarious, although kind of sad.

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They have really stubby legs, who is five years old, also made that cat up.

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So some terminology.

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When we're talking about tables and you hear the term columns, it's referring to the headers on that

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table.

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So what are the different components of data, the different pieces that have to be there?

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In our case, we have name, breed and age.

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So those are the columns, and then the rows are the actual data in the table.

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So here's a row blue.

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The cat is one row, rocket is another row.

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Monty is another row.

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Sam is another row.

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I really wish that was lined up correctly, but I just drove myself nuts trying to get it to work.

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Please forgive me anyways.

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So databases are made up of lots and lots of these tables.

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It's usually not just one.

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If you have a really, really simple app and you're just storing one thing, then it will just be one.

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But usually apps are pretty complicated and data is complicated.

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All that we modeled there was cats.

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But imagine if this was actually an app, let's say it was a pet sitting app.

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And cats were one thing that we had to keep track of.

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But we also have to keep track of owners and the pet sitters and addresses and dates and appointments

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and payments.

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And those are all going to be tables.

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Some of them might even be multiple tables, but for now we're not going to really worry too much about

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that.

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But just to show you, sometimes it does get crazy.

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You can click this link or I'll click it, follow my own instructions.

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To see the breakdown of some of the tables that Facebook's database or a social network might use in

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their database.

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So this is not actual this is not 100% accurate.

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There are things that are missing or incomplete.

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But this just shows all the different tables, or at least some of the different tables involved in

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a pretty complex app.

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So as you can see, there is a bunch of them here, things like account and event and message and notification,

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website, screen, name, address, blah, blah, blah, all these different things to take into consideration

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so things can get messy.

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And as we progress in this course, you will start working with multiple tables.

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You'll see how they connect.

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But we haven't even seen how to create a single table yet, so we're going to focus just on individual

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tables and then we'll move on from there.