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Okay.

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So what we've seen so far allows us to specify what columns we want.

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Name an age only or only ID, but it still gives us every single result in the table.

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So if we have 10,000 users in our database, if we wanted to select one, we don't have a way of doing

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that right now.

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We only can select all of them, which really is not that useful.

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And in fact, most of the time when you're selecting things, you're doing it deliberately and you're

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trying to find particular pieces.

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You're not just trying to check in on your table, make sure everything's okay.

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You're usually trying to, let's say, sign someone in.

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It's an application you're trying to verify, find someone by their username and check if their password

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matches that they entered into your website or something like that where you're searching for specific

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data.

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And to do that, we need to use what's known as the where clause.

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So it's another magic keyword where, and it allows us to get specific.

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It allows us to say, I want all cats who are four years old or I want all cats who are tabbies.

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And those are very simple examples.

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But later on, throughout this course, we'll continue to expand your arsenal for select and for searching.

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You'll be able to do things like I want all cats that are Tabby is between the age of one and two and

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whose name starts with the letter B, let's say.

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So we'll be able to get much more specific.

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But for now we're focusing on the basics.

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And as a side note, I want to show you that we will use where all the time.

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So it's not just for searching or for selecting, but we'll need to use it when we're updating or deleting

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things as well, because unless we're trying to update every single thing or delete every single thing,

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usually we want to update something specific.

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So we might say, I want to update the cats where their age is too, and I want to make their age three.

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Versus I want to update every single cat to have an age of three.

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We could be more targeted using where.

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So we're going to start by seeing how we use it to select.

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So here's an example select star from Cats where age is four.

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So notice the syntax.

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Here we have our same select star from cats that will give us all cats.

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But then we have this where age equals four.

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So what this will do is only select the data from the Cats table where the age column is equal to four.

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And if we try that now, if we look at our data actually, you'll see we have two cats, Ringo and Egg,

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who are both four years old.

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So if we do a select star from Cats, you see what we get.

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But now if we modify that with our where age equals four semicolon, we only get those two results.

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So we still get cat ID, name, breed and age because we use star that tells us the columns.

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But now we only have two results because we used where to get specific.

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One note notice that when I refer to age here, that is the column age.

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So there's no quotes around it, it's just age.

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So we can do the same thing here.

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But this time I'm using name to drill down or to get specific.

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So select star from cat where name is equal to egg.

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And notice I use quotes here because it's no longer an integer like ages.

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Name is fa cha, it's text.

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So we need those quotes so we can try that.

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Now.

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Select star from cats where name equals egg just like that.

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And you notice we get egg cat id, name, breed and age.

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One side note while I'm here, you may come across this at some point.

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What do you think will happen if I fully capitalize egg?

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It still works.

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So it's important to note that by default this is case insensitive.

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So I could do lowercase g, uppercase g and it still gives me the same data.

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So we'll see ways around this later on.

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Oftentimes it is useful, though, to not worry about case if you're dealing with things like an email

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address where case doesn't actually matter.

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So if a user types in their email with a capital letter at the beginning versus lowercase, it should

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still be the same email in your database, but we'll talk about that later.

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I just wanted to point out that it's a thing, case and sensitivity.

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So that's all there is for now to the WHERE clause.

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Now there is a lot more that we will be seeing and working with.

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Like I mentioned at the beginning of this lesson, we will come back and use where all the time and

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in fact we're going to continue to use it for updating and deleting.

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Like I said, we need to specify what we want to delete and what we want to update.

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But I just want to make it clear we're not done with where there's a lot of add on functionality that

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we'll see in ensuing sections.

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Perfect.