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The next thing we have to talk about around tables are data types.

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So when we define the structure of a table, we're not only saying what column names we want, for example,

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you know, name, breed and age, but we also specify the types, what type of information is permitted

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in each column.

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And this is really, really important.

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Imagine we have our name, breed and age for the cat's table, where age is just left up to be whatever

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a user puts in there.

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So it could be a number one three or the word ten or I am young cat, whatever it is, there's no rules

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being enforced.

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It might make sense that it should be a number, but it doesn't say in our example at least that it

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has to be a number that leads to a lot of problems.

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If we try and then do stuff with our data, if we try and multiply it by seven to get a rough approximation,

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converting between cat years and human years, or vice versa, human years and cat years.

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To get the cat age, you multiply by seven, which is actually not really correct.

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That's a super simplification.

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It's not some easy formula.

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I looked it up recently, but this is good enough.

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I want to multiply it by seven.

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So one time seven.

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That's easy.

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Three times seven, That's easy.

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Ten times seven.

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We have a problem.

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The word ten times seven.

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And I am young cat time seven.

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It's just not going to work.

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So we need consistency of our types.

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We need not just to say what this column is called, but also what content it contains, what type of

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information.

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I want to say something like Name has to be text, breed has to be text, age has to be a number.

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So in the world of MySQL, we have a lot of different data types.

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It's honestly kind of overwhelming.

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The good news is that there's a handful you'll use a lot.

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But let me just show you, we have different types for numbers.

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You might think there's just a number type that's not true.

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Unfortunately, we have a type called integer or int, then we have small int and even smaller we have

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tiny int and then medium int and then big int and then decimal and then numeric and then float and then

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double and bit.

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It gets just absolutely crazy if you try and master or learn the, the differences between all of these

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up front.

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So don't, don't worry about it, but just know that there are a lot of different types.

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Same thing for string types or text types.

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We have char or car.

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I guess you should pronounce it car because it's character.

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But I've always said char, even if that's incorrect.

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Var char var car binary.

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Var binary blob tiny blob medium blob long blob text tiny text medium text long text enum.

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So these are all different categories of text information and there's differences.

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That's why they exist.

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But a lot of the differences are very slight.

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So we've got numeric types, string types, and we also have date types.

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So date, date, time, time stamp, time and year.

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It's a little crazy.

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If you ever get confused or you have questions, the first thing you should do is head to the docs.

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There's a page about data types and the documentation and the reference manual.

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So if you want to know more about, I don't know, string data types or numeric data types, click on

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that and then you'll see the different categories and then you can click to get more specific.

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If I want to learn more about small int, whatever that is compared to int, I can click here and it

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will tell me I can find out the rules and we're going to dive into some of this stuff later in the course.

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So for now we really don't need to worry.

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You should just know that there are different categories of information, different types, and there's

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two specifically that we're going to work with right now Integer or int for short and var kar or var

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char, which is a text or a string data type for textual information.

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So let's talk a bit more about int, int or integer.

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You can write it either way, but int is nice and short is a whole number.

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So no decimals and it has a maximum value of this number right here.

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But this is a maximum signed value, meaning that we could also have negative this value.

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So negative or positive, you can have a larger maximum value if you set it up in such a way that you

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don't allow signed values.

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It's unsigned, but we really don't need to worry about that.

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I just need to put that in there to be specific.

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But at the end of the day, it's a whole number and unless you're dealing with really big whole numbers,

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you really don't need to worry about the maximum size.

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So something like 12, that's a valid int -9999 valid int so is zero, so is 3145677 or 42.

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Those are all integers.

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Now we have var char or var kar, which is a variable length string, that's the var parts.

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There's also just a data type called car or char that is not variable length and we'll see that later.

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So when I say variable length, that means that we can store something that is this many characters,

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but is that four or five, six, seven, eight characters long or this many characters?

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Now this is a number, but notice it's in quotes, meaning it is treated as text or this many characters

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or a single character or a whole sentence, 26 plus characters, way more than 26.

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Whatever a number of characters this is, it's a variable length.

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So var is really commonly used because a lot of the time our textual information does vary in length.

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Think of people's usernames.

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Somebody might have the username colt.

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That's nice.

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They were there early.

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It's for characters, but somebody else might have to have Colt four or five, six, seven and so on.

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It's more characters.

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So that's bar car an INT the two basic data types we're going to start with.

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Now, the next thing you need to know is that when we create a table and we assign the data types with

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VAR car, we can actually specify a maximum number of characters allowed.

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So with var card or var char, I can say maximum of 100 characters for name and let's say for breed

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the same thing.

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Maybe I want it smaller.

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It's hard to say.

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Is there going to be a cat name that's 100 characters or more?

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Maybe, maybe not.

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But this allows me to specify a maximum size so it can still vary between zero and 100 characters,

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but the maximum is 100 characters that will store in this column for each row and then for int, we'll

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just say int and this just says an integer of any size, assuming it fits within those bounds that I

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showed you that really large number, we can go anywhere up to that size.

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So for age it's going to be fine.

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Although something we might want to consider is is age best stored as a whole number?

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What about fractions or decimals?

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Because right now that is not an option if we're using integer, but that's for another section coming

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up.

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So I'm going to stop here because it's a long video.

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We covered a lot.

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The basic concept is that there are all these different data types in the world with my SQL ten plus

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number data types and ten plus string or text data types, not to mention dates and times and even other

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things like spatial data types.

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These are all different types that we can assign to columns in a table and then the database.

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My SQL will enforce those types.

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So with VAR car, that's the one we're focusing on for text four Now it represents or it stores text

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of variable length up to whatever size we specify in those prints.

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And then int we'll store whole numbers.

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Next up, we've got a quick little activity.