WEBVTT 00:00.120 --> 00:01.040 So that's the basics. 00:01.080 --> 00:05.660 But there's another wildcard character that I'll show you which is the underscore. 00:05.970 --> 00:09.250 So here I have a really weird query. 00:09.270 --> 00:13.660 This is for underscores in a row they will have to trust me that it's four. 00:13.890 --> 00:17.070 And it was hard to tell what this will do. 00:17.310 --> 00:24.690 So we're searching stock quantity which is a number and we're trying to find where it's like for underscores 00:25.190 --> 00:31.380 and basically an underscore is a wildcard to specify exactly one character any character but exactly 00:31.380 --> 00:31.870 one. 00:31.920 --> 00:37.510 So four of them in a row is saying I want to find where the stock quantity is for characters long. 00:37.980 --> 00:41.110 So let me show you why we might want to do that. 00:41.130 --> 00:50.390 Why do a select stock title and stock quantity from books just like that. 00:50.520 --> 00:58.000 You can see that we have Star quantity of to her sorry two digit two tickets 32 43 three. 00:58.150 --> 01:00.190 She is giving me a tough time. 01:00.300 --> 01:02.520 Digits 154. 01:02.970 --> 01:09.450 And then this great book linking in the bardo has a thousand copies in stock is brand new. 01:09.450 --> 01:10.860 People don't know about it yet. 01:11.130 --> 01:11.730 They're not buying it. 01:11.730 --> 01:13.140 I'm sure people will buy it soon though. 01:13.170 --> 01:16.400 Once Of course they they realize what a great book it is. 01:16.410 --> 01:23.190 So if I wanted to select books where stock quantity is four digits long I could use that wild card. 01:23.220 --> 01:24.490 So let me just say that again. 01:24.570 --> 01:32.190 So select title and stock only from books where stock on or the like. 01:32.940 --> 01:39.580 And all I have to do so just to clarify if I did this that wild card just means anything. 01:40.020 --> 01:41.810 So that's going to give us everything. 01:42.060 --> 01:44.330 And if I do four of them it doesn't make a difference. 01:44.610 --> 01:46.230 That's not saying four characters. 01:46.230 --> 01:49.060 That's just four different ways of saying anything at all. 01:49.080 --> 01:50.190 It could be nothing. 01:50.190 --> 01:53.550 It could be a thousand characters it doesn't matter. 01:53.550 --> 02:03.660 So by adding underscores that's for there you'll see I get Lincoln in the bardo or I could do two underscores 02:04.620 --> 02:07.980 and I only get the two digit stock quantities. 02:07.980 --> 02:11.250 Now that's not to say the only time you use underscores is when you're trying. 02:11.340 --> 02:11.690 Yes. 02:11.700 --> 02:13.630 Blue is my cat. 02:14.070 --> 02:15.230 Are you going to say hi. 02:15.450 --> 02:17.520 She's now sitting on the computer. 02:18.240 --> 02:18.520 OK. 02:18.540 --> 02:20.620 So back to where I was. 02:20.730 --> 02:23.450 Get this cat hair out of here. 02:23.490 --> 02:29.920 The underscore is not only used and actually it's not even primarily used for counting digits like that 02:30.240 --> 02:33.480 but it's a way of specifying exactly one character. 02:33.480 --> 02:38.460 Like I said Let's say that we're working with phone numbers and in the US they might look something 02:38.460 --> 02:39.630 like this. 02:39.660 --> 02:45.120 So we have an area code in parentheses and then three digits dash four digits. 02:45.440 --> 02:51.900 And if we wanted to match that pattern we would have something that looks like this like and we'd have 02:51.900 --> 02:58.020 a first print to see and if we just put this wildcard there that's going to say any number any letters 02:58.020 --> 03:04.590 whatever it is in between those parentheses but we're actually looking for three digits and then another 03:04.590 --> 03:06.280 three digits after that parentheses. 03:06.510 --> 03:09.380 Then a dash and then four digits. 03:09.990 --> 03:15.750 So basically we have these two wild cards at the end of the day present sign which means anything or 03:15.750 --> 03:16.580 nothing. 03:17.130 --> 03:20.530 And then underscore which is exactly one thing. 03:20.790 --> 03:26.500 And you can chain them together to match patterns then that brings up another question which is but 03:26.510 --> 03:30.290 what if I'm searching for a book that has a percent sign in it. 03:30.540 --> 03:32.140 How would I do that. 03:32.190 --> 03:39.030 And you may have noticed that I expertly planted a book title with the percent sign and I was thinking 03:39.030 --> 03:41.010 ahead for once. 03:41.010 --> 03:43.180 How would we select that. 03:43.410 --> 03:47.730 Or there's also a book title that it's not so creative It has an underscore in it. 03:47.730 --> 03:49.110 How would I select that one. 03:49.350 --> 03:56.910 If these characters are special wildcard characters how do I actually search for the exact character 03:57.060 --> 04:00.010 percent side or the exact character underscore. 04:00.030 --> 04:03.440 And the answer is actually pretty straightforward. 04:03.900 --> 04:07.230 We use what's known as an escape character. 04:07.560 --> 04:14.250 In this case I always forget which one is backwards and forwards slash but whichever slash This is the 04:14.250 --> 04:15.860 one over the turkey. 04:15.900 --> 04:23.300 Pretty sure that his backslash so backslash percent signed is going to match a percent sign. 04:23.310 --> 04:27.830 So this entire thing right here is basically saying percent sign. 04:28.470 --> 04:32.510 Likewise with underscores backslash underscore is the escape character. 04:32.760 --> 04:34.710 So let's put that into practice. 04:34.740 --> 04:35.650 Let's try it out. 04:35.670 --> 04:44.430 So a select title from books and we'll just do that first all and you'll see we've got 10 percent happier 04:44.820 --> 04:46.110 and then fake under scorebook. 04:46.110 --> 04:47.830 So let's start with 10 percent happier. 04:48.090 --> 04:56.220 So I want to select title from books from books where title like and just I mean this should be clear 04:56.220 --> 04:56.480 right now. 04:56.490 --> 05:01.490 But if we tried to do this that's not going to work that's going to give us everything. 05:01.740 --> 05:07.770 But if I tried to say okay percent signed that means anything and then a percent signed and then anything 05:07.770 --> 05:12.090 afterwards that's not going to work either because that's basically just three different ways of saying 05:12.270 --> 05:13.890 anything at all in the title. 05:13.890 --> 05:17.040 So that's where we need our backslash. 05:17.060 --> 05:24.000 Now you could read this as you could condense this to say exactly a percent sign 1 percentage sign anything 05:24.000 --> 05:25.870 before anything after. 05:26.370 --> 05:27.200 And there we go. 05:27.360 --> 05:30.210 That's how we get 10 percent happier. 05:30.210 --> 05:31.540 Same thing with the underscore. 05:31.640 --> 05:33.630 I won't go through that whole routine again. 05:34.620 --> 05:41.950 We just replaced that backslash present with backslash underscore and that gives us fake book. 05:41.980 --> 05:42.540 All right. 05:42.720 --> 05:45.480 So that's all there is to like for now. 05:45.840 --> 05:47.080 It's very very useful. 05:47.130 --> 05:49.090 We'll be using it quite a bit in this course. 05:49.110 --> 05:54.100 It's probably one the most commonly used things in my school are in school when doing queries. 05:54.330 --> 05:59.970 In all likelihood you won't be matching percent signs or underscores all that often but you'll be doing 05:59.970 --> 06:06.390 things like this all the time where you're using the percent wildcard and the underscore wildcard to 06:06.390 --> 06:07.460 match patterns. 06:07.810 --> 06:08.300 OK. 06:08.340 --> 06:09.600 Next up exercise is.