Functions

Quick reference

• 00:00 In this video I wanna to look at some of the built-in
• 00:06 functions we can use to calculate data.
• 00:10 So we've already looked at one of these when we looked at the count function
• 00:13 earlier, but we're gonna drill down and look at a few more in this video.
• 00:17 First off, I should mention that,
• 00:19 just gonna copy this, you can do basic math with the select statement.
• 00:22 So 2 + 3, if we execute this, we get 5.
• 00:27 And you can use all of the basic math you think.
• 00:30 Multiplication, 2 times 3, 2 divided by 3, all of your basic math sort of things.
• 00:37 Let me change this to 6.
• 00:39 We can do, so that's kind of cool and that's sort of useful, but
• 00:43 there are also built-in functions that we can play around with.
• 00:46 And in this video I wanna just look at three of them, we're gonna look at count,
• 00:49 average, and sum.
• 00:51 And like I said, we've already used count in the past.
• 00:54 And whenever you do a function, you just name the function and then you use these
• 00:58 little parentheses and then inside of here you pass whatever you want to pass.
• 01:01 So if we wanna count the number of rows we have in the age column,
• 01:06 we have six rows just like that.
• 01:09 We can also do a sum, so
• 01:11 if we wanna add up all of the values in the age column, comes to 197.
• 01:17 We can also do average, AVG.
• 01:21 And we get 32.
• 01:22 So these things, there's a lot of little built-in functions like this.
• 01:25 You can do a little research to learn some of the other ones.
• 01:28 We don't have time to go into all of them in this course, but
• 01:30 they're all pretty much this easy to use.
• 01:32 You just name the function, put them in these parenthesis, and
• 01:35 then you pass inside whatever you wanna do.
• 01:38 Now obviously, the data type is important here.
• 01:41 If we tried to average, for instance, First Name.
• 01:48 We're gonna get an error, because you can't add letters, right?
• 01:51 It just doesn't work.
• 01:52 And also I should mention I'm typing in Age, as in the past,
• 01:56 we should probably be putting these in brackets, but it works either way.
• 01:59 So I mentioned at the beginning of this video, you can do basic math.
• 02:03 You can also use these different things to do basic math.
• 02:06 For instance, if we do sum of Age, we have 197.
• 02:10 Now if we wanted to count how many rows there are,
• 02:16 we could do COUNT Age, and so we get 6 columns.
• 02:22 The total sum of all of the values in those columns is 197.
• 02:26 Well, to get an average, you take the total sum divided by the number of things.
• 02:31 So we could easily just divide, put the little division sign right there,
• 02:36 run this, and get 32.
• 02:37 Which is the same as when we ran our average earlier, when we get 32.
• 02:44 So lots of different ways you can play around with these different functions.
• 02:48 Lots of different things you could use them for.
• 02:50 Just use your imagination and I'm sure you can think of a lot of different things.
• 02:53 And like I said, there's a lot of different functions you can learn.
• 02:55 I'm just giving you a taste in this video to show you some of the most basic
• 02:58 ones for calculations.
• 03:00 So up until now, we've been pulling stuff out of our database and displaying it.
• 03:04 In the next section we're gonna look at actually putting data in using SQL.
• 03:09 And we're gonna look at the insert statement.

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