WEBVTT 00:00.290 --> 00:06.060 OK so we've made it through the C R and you portions of crud. 00:06.060 --> 00:11.430 Now we finally made it to D which stands for delete or destroyed depending on who you ask. 00:11.430 --> 00:17.970 So in this video we're going to see how to do things in my ask you will well and it's pretty straightforward. 00:17.970 --> 00:24.330 It's very similar to selecting things except rather than just selecting something you're going to delete. 00:24.330 --> 00:26.260 So let me show you what I mean. 00:27.030 --> 00:32.970 Here's an example that will delete any cat with the name eg in our database. 00:32.970 --> 00:40.110 So imagine first of all that we were selecting all we would have is select from cats where name is equal 00:40.110 --> 00:41.010 to egg. 00:41.400 --> 00:48.650 So if we ran that it would give us the cat or cats with name egg and we can swap out select with delete. 00:48.830 --> 00:49.950 And that will delete it. 00:49.950 --> 00:56.400 So that same rule of thumb from before where I said Make sure you update something that your selection 00:56.460 --> 00:57.270 is correct. 00:57.360 --> 01:01.500 Then do the update because it will I mean there's no undo button unfortunately. 01:01.560 --> 01:07.190 Same holds true and more so with delete because your data is gone as soon as you delete it. 01:07.200 --> 01:08.660 So let's try this will delete. 01:08.700 --> 01:09.490 Eg. 01:10.120 --> 01:10.910 Let's do. 01:10.920 --> 01:13.550 First of all it's like start from cats. 01:13.620 --> 01:16.060 Just make sure we have egg in here. 01:16.080 --> 01:17.610 There he or she is. 01:17.610 --> 01:21.840 I'm not quite sure what I was intending with that name. 01:21.840 --> 01:22.350 Eg. 01:22.410 --> 01:27.360 So what we'll do first is just make sure we can select appropriately before we delete. 01:27.770 --> 01:34.740 So select star from cats where name equals eg. 01:34.890 --> 01:37.760 Remember that this is case insensitive. 01:38.010 --> 01:38.940 Just for now. 01:39.330 --> 01:41.200 I'll do lowercase just to prove that. 01:41.280 --> 01:43.200 All right so we get egg perfect. 01:43.530 --> 01:52.100 So now to remove egg delete from and then we can just copy this. 01:52.310 --> 01:58.670 So before I hit enter I do need to take a moment to address something pretty serious and that is that 01:58.670 --> 02:02.330 no cats are being harmed no cats are dying here. 02:02.630 --> 02:08.290 Yes they're being deleted from this table but in reality deletion doesn't mean death. 02:08.390 --> 02:10.630 It means that they're being adopted. 02:10.640 --> 02:15.710 Perhaps to a loving family that will treat them with the care that they deserve. 02:15.950 --> 02:21.360 So there's no death here and I hope I don't receive any Furius comments about how I'm treating animals 02:21.360 --> 02:21.860 in my course. 02:21.860 --> 02:23.030 I love animals. 02:23.090 --> 02:24.950 I learned from my first course. 02:24.950 --> 02:25.930 I made a mistake. 02:26.180 --> 02:31.320 I will never refer to deleting dogs or cats as killing them. 02:31.780 --> 02:33.250 I'm very sorry for that. 02:33.740 --> 02:36.050 So again these cats are not dying. 02:36.050 --> 02:38.480 So with that out of the way let's hit Enter 02:41.740 --> 02:52.210 now let's go back and select star from cats and as he can see eg is now gone. 02:52.210 --> 02:54.850 Also something that does come up sometimes. 02:54.880 --> 02:58.030 Notice that the cat ID's have not shifted. 02:58.030 --> 02:59.160 They're still the same. 02:59.170 --> 03:04.750 Some of my students in the past have had the expectation that the IDs would alter but they always will 03:04.750 --> 03:05.610 stay the same. 03:05.920 --> 03:12.240 And that's because when something is inserted into a table that unique ID is generated for it remembers 03:12.250 --> 03:18.700 the primary key and eventually will learn about having multiple tables that interact with one another 03:18.970 --> 03:22.460 and will be storing these ideas in other tables. 03:22.780 --> 03:28.470 So if it changed that could be problematic because we'd have to change it in multiple places anyways. 03:28.620 --> 03:33.830 I'm trying to say is that we removed 4 but we still have 5 6 and 7. 03:33.850 --> 03:36.910 This didn't change to 4 and change to 5 and so on. 03:36.910 --> 03:39.440 All right so we deleted that rest in. 03:39.490 --> 03:43.280 I mean enjoy your new life with your happy family eg. 03:43.690 --> 03:48.780 So one last thing here is that if you look at what I've written here delete from Cats. 03:49.060 --> 03:50.330 What do you think that will do now. 03:50.330 --> 03:53.270 I don't run it but what do you think this would do. 03:54.280 --> 03:56.790 And the answer is that it deletes everything. 03:56.980 --> 03:58.390 All cats. 03:58.580 --> 04:00.740 They're all released to their happy families. 04:01.330 --> 04:04.500 So that's important to know that you can do that. 04:04.690 --> 04:09.580 So it's different than dropping a table because dropping a table gets rid of the table entirely and 04:09.580 --> 04:15.190 all data inside of it but deleting from cats just deletes the entries in the cat's table. 04:15.190 --> 04:16.570 But we still have the shell. 04:16.570 --> 04:18.070 We still have the cats table. 04:18.340 --> 04:21.240 There shouldn't be very many times when you need to use this command. 04:21.640 --> 04:26.500 I'm not going to do it just yet because I want us to have our cat's data for a little bit for the next 04:26.530 --> 04:31.730 exercises but just keep that in mind because we didn't specify a WHERE clause over here. 04:32.890 --> 04:35.200 It's the same as selecting without a WHERE clause. 04:35.200 --> 04:37.770 It's like everything so this will delete everything. 04:38.160 --> 04:40.900 OK next up you're going to practice deleting.