WEBVTT 00:00.180 --> 00:02.520 OK so we're moving on in this video. 00:02.610 --> 00:05.190 We're talking about default values. 00:05.310 --> 00:07.160 What's up with this part right here. 00:07.350 --> 00:11.930 Default So as we talked about a little bit in the last video it's helpful to be able to decide or to 00:11.930 --> 00:13.590 set default values. 00:13.590 --> 00:18.340 So if something is not specified that there will be a fallback. 00:18.750 --> 00:20.220 And here's how we do it. 00:20.340 --> 00:22.690 We use default. 00:23.010 --> 00:28.190 So you can see both of these when we're defining a table default and then we specify a default. 00:28.260 --> 00:36.150 So for name if you leave off name I just said OK we'll call it unnamed or name to be determined sometimes 00:36.350 --> 00:42.780 if this is a cat shelter in the real world sometimes they decide on a name a little bit later once they 00:42.780 --> 00:48.180 figure out the cat's personality and then for age if this is more of a silly example but if we wanted 00:48.180 --> 00:52.830 to if you didn't specify age we could always set it to be ninety nine. 00:52.920 --> 00:57.070 Not sure why but for the sake of this exercise we're going to do it. 00:57.240 --> 00:58.490 So let's give it a shot. 00:58.650 --> 01:02.180 Remaking a new cats table cat 3. 01:03.210 --> 01:04.590 OK here we go. 01:04.630 --> 01:11.540 So create table cats 3 and I'll do a new line here. 01:13.560 --> 01:18.140 And we will have a name for our car. 01:18.180 --> 01:20.800 Let's do 20 even though my slides say 100. 01:20.830 --> 01:21.440 It's OK. 01:21.780 --> 01:25.690 Default in our default will be. 01:25.840 --> 01:29.240 That's a no name provided. 01:29.250 --> 01:30.750 How about that. 01:30.930 --> 01:36.690 It's important that whatever you put here matches the data type so we couldn't say the default is the 01:36.690 --> 01:38.860 number 100. 01:39.450 --> 01:47.130 And then we'll have our Khama age and age isn't it. 01:47.590 --> 01:54.790 Default should be 99 perfect clothes that. 01:55.110 --> 02:01.030 Now if we do our describe cats 3 Here we go. 02:01.380 --> 02:07.760 So we have default no provided default 99 for H. 02:07.800 --> 02:08.380 Awesome. 02:08.580 --> 02:18.700 OK so now let's give it a shot let's do insert into Cat 3 and I'll do. 02:19.380 --> 02:20.260 Age only. 02:20.280 --> 02:27.320 And no name and age will be let's do 13 just like that. 02:27.330 --> 02:34.170 What do you think will happen going to insert a new cat into Cat 3 which is right here only for fighting 02:34.200 --> 02:40.000 age and name has a default value of no name provided. 02:40.540 --> 02:41.640 Ok I did it. 02:41.650 --> 02:46.720 Now let's look like Star from Cat 3. 02:47.420 --> 02:49.760 And I get no name provided. 02:49.980 --> 02:50.670 Perfect. 02:50.670 --> 02:53.000 So we have a default value that's working great. 02:53.100 --> 02:55.080 We could do the same thing for age. 02:55.080 --> 03:00.330 Feel free to skip this if you feel like you know exactly what's going to happen. 03:00.330 --> 03:00.900 I'll leave. 03:00.930 --> 03:07.960 Let's leave both off this time and certain to catch three values. 03:08.450 --> 03:09.440 Now when we select. 03:09.650 --> 03:14.720 We have another unnamed cat this time who is ninety nine years old by default. 03:14.870 --> 03:21.830 So the next thing that I want to talk about here is another version of creating a table for cats for 03:21.890 --> 03:22.470 this time. 03:22.610 --> 03:26.820 And I combined not know all along side default. 03:26.990 --> 03:33.420 Otherwise it's the same so we have name our car default this unnamed age it default that's 99. 03:33.650 --> 03:36.040 But I didn't not no. 03:37.190 --> 03:44.180 And as I wrote here you might be thinking isn't this redundant because if we have a default value it's 03:44.180 --> 03:46.470 already saying it won't be no. 03:47.120 --> 03:57.720 If we go back and we look at cat's regular cat if we do an insert into cats just like this. 03:57.720 --> 04:08.240 And if you can remember all the way back to cats we have no default provided and you select star from 04:08.240 --> 04:10.730 cats we get. 04:10.730 --> 04:14.130 No no there's no default values. 04:14.240 --> 04:22.910 And then when we have our cat 3 when I insert something like this right here incertain to Cat 3 it's 04:22.910 --> 04:24.530 totally empty. 04:24.530 --> 04:26.010 We have those defaults. 04:26.030 --> 04:35.140 So when I select star ups from Cat 3 we get no name provided. 04:35.140 --> 04:36.410 Ninety nine. 04:36.950 --> 04:39.000 So why would we want to add. 04:39.020 --> 04:39.970 Not no. 04:40.250 --> 04:45.680 And the answer is that we could still manually set something to be no. 04:46.130 --> 05:00.140 So if I did that here let's do insert into Cat 3 and I'll do name and age name and age values and I 05:00.140 --> 05:06.180 will say there's no name or let's say name is what's another state in Montana. 05:06.350 --> 05:07.960 It's not too bad for a cat's name. 05:08.120 --> 05:09.650 Great state by the way. 05:10.100 --> 05:15.170 And we'll leave age as no explicitly no. 05:15.470 --> 05:16.230 Just like that. 05:17.800 --> 05:26.900 That to do so like star from got three and you can see that there is nothing stopping us from setting 05:26.900 --> 05:33.010 age to be no all that we have it's a default value if you don't specify something it will be 99. 05:33.140 --> 05:38.980 But you're allowed to say no I'm allowed to say this is explicitly an empty value. 05:39.400 --> 05:39.880 OK. 05:40.040 --> 05:45.320 So that's where this comes in name for which are not. 05:45.320 --> 05:45.850 No. 05:45.950 --> 05:47.050 And a default. 05:47.540 --> 05:49.780 And I won't make you sit through me typing that whole thing. 05:49.790 --> 05:53.700 So I'll just copy it but to walk through it again. 05:53.930 --> 05:55.520 Same thing here. 05:55.520 --> 05:59.420 Same with the default We just did not know and not know. 05:59.630 --> 06:03.040 So let's go ahead paste this in. 06:03.200 --> 06:07.190 This is Katz for this time. 06:07.190 --> 06:15.830 If I do describe cat 4 we now have no is no on both and we have a default on both. 06:16.400 --> 06:17.750 So we're almost there. 06:17.750 --> 06:19.860 I know spend a little bit of a long video. 06:20.120 --> 06:31.450 Let's do a insert into cat 4 and we will specify name and then age. 06:32.360 --> 06:41.590 And this time if I do values AUPs and I say name is what's in it. 06:41.600 --> 06:43.630 Let's do Cali fine. 06:43.700 --> 06:47.410 Sort of a state name and age is no. 06:47.690 --> 06:52.150 If I do this this time we get an error. 06:52.450 --> 06:56.650 So not just a warning but an error saying it cannot be No. 06:56.850 --> 06:57.760 And that's what not. 06:57.810 --> 07:04.300 No specifies so important to note that you'll use not know pretty often. 07:04.360 --> 07:09.880 It's a way of basically requiring that something has a value but also saying that it's not allowed to 07:09.880 --> 07:15.380 be know itself which I also included as a slide here in Cat 3. 07:15.430 --> 07:17.140 We can manually insert something as.