WEBVTT 1 00:00:00.100 --> 00:00:01.310 Hi guys and welcome back. 2 00:00:01.310 --> 00:00:03.140 In this video we're going to deconstruct 3 00:00:03.140 --> 00:00:05.820 the Select statement for you. 4 00:00:05.820 --> 00:00:07.110 Here we've got an example, 5 00:00:07.110 --> 00:00:10.960 SELECT first_name, surname FROM users. 6 00:00:10.960 --> 00:00:12.820 The first part tells the database 7 00:00:12.820 --> 00:00:14.950 that we want to find and retrieve data. 8 00:00:14.950 --> 00:00:17.140 That's what the SELECT is for. 9 00:00:17.140 --> 00:00:20.730 Then the columns that we want to retrieve data from, 10 00:00:20.730 --> 00:00:24.950 or what we want the final result set to contain. 11 00:00:24.950 --> 00:00:26.830 And in the final result set, we're gonna get the 12 00:00:26.830 --> 00:00:31.230 first_name and surname columns of the users table. 13 00:00:31.230 --> 00:00:34.930 Note that, if the users table had five columns, let's say, 14 00:00:34.930 --> 00:00:37.750 we would only get data from the first_name 15 00:00:37.750 --> 00:00:39.610 and surname columns. 16 00:00:39.610 --> 00:00:41.670 There's a lot more to do with SELECT. 17 00:00:41.670 --> 00:00:43.580 We can filter the selected data 18 00:00:43.580 --> 00:00:46.240 so that we only get rows with certain values, 19 00:00:46.240 --> 00:00:48.810 and we can use the WHERE clause for that. 20 00:00:48.810 --> 00:00:49.870 We're gonna use it later on, 21 00:00:49.870 --> 00:00:51.690 We're gonna learn more about that. 22 00:00:51.690 --> 00:00:54.930 We can also select data from multiple tables at once 23 00:00:54.930 --> 00:00:57.210 and we're gonna use JOIN for that, 24 00:00:57.210 --> 00:00:59.140 we're going to learn more about that later on. 25 00:00:59.140 --> 00:01:01.850 This is for what we spoke about earlier on in the course, 26 00:01:01.850 --> 00:01:06.350 regarding Relational Data, we'll be using JOINs to do that. 27 00:01:06.350 --> 00:01:08.980 All right, let's go and write some SELECT statements 28 00:01:08.980 --> 00:01:11.050 over in the Database Viewer. 29 00:01:11.050 --> 00:01:13.990 All right, let's go into DB Browser and start looking at 30 00:01:13.990 --> 00:01:17.540 how we can retrieve data using SELECT queries. 31 00:01:17.540 --> 00:01:20.430 Here I'm in the Browse Data tab at the moment and 32 00:01:20.430 --> 00:01:23.480 you can see I've got five rows of data in my users table. 33 00:01:23.480 --> 00:01:27.140 We're gonna use this test data to run our queries against. 34 00:01:27.140 --> 00:01:29.700 If you want to insert some test data into your table, 35 00:01:29.700 --> 00:01:32.670 pause the video now and do that, as well. 36 00:01:32.670 --> 00:01:34.470 Let's go over to execute SEQUEL, 37 00:01:34.470 --> 00:01:37.520 and here we're going to start with a SELECT. 38 00:01:37.520 --> 00:01:39.440 Again, this tells SQLite that we want to 39 00:01:39.440 --> 00:01:40.980 start retrieving data. 40 00:01:40.980 --> 00:01:44.350 The next part of the query must be the columns 41 00:01:44.350 --> 00:01:46.150 that we want to retrieve. 42 00:01:46.150 --> 00:01:48.720 So, for example, first_name and surname. 43 00:01:48.720 --> 00:01:51.440 We don't have to put brackets around these, 44 00:01:51.440 --> 00:01:53.790 just like that is fine. 45 00:01:53.790 --> 00:01:57.870 Then FROM users tells SQLite that this is a table 46 00:01:57.870 --> 00:02:01.780 we want to retrieve data for these columns from. 47 00:02:01.780 --> 00:02:04.610 So if we run this, you can see now down here, 48 00:02:04.610 --> 00:02:08.750 we've got our five rows retrieved. 49 00:02:08.750 --> 00:02:11.280 You can just retrieve data from one column, of course, 50 00:02:11.280 --> 00:02:13.070 and then you just get that column back 51 00:02:13.070 --> 00:02:15.770 for all the rows in the table. 52 00:02:15.770 --> 00:02:19.010 And, if you use the asterisk, or the * sign, 53 00:02:19.010 --> 00:02:21.800 you can retrieve data from all columns. 54 00:02:21.800 --> 00:02:23.920 At the moment, this looks the same as earlier on, 55 00:02:23.920 --> 00:02:26.110 but if you had more columns, then these would all 56 00:02:26.110 --> 00:02:27.683 show up when you use the star. 57 00:02:28.620 --> 00:02:30.850 Like we mentioned earlier, you can filter the data, 58 00:02:30.850 --> 00:02:32.540 and you can select data from multiple tables. 59 00:02:32.540 --> 00:02:35.010 We're going to learn more about that as we move on 60 00:02:35.010 --> 00:02:36.280 through the course. 61 00:02:36.280 --> 00:02:37.700 Thank you for watching this video. 62 00:02:37.700 --> 00:02:39.313 I'll see you in the next one.