WEBVTT 00:05.360 --> 00:07.070 Have room and welcome back. 00:07.120 --> 00:10.270 So in this video we're going to be talking about queering Dockum. 00:10.280 --> 00:14.230 So how can we query the documents that we inserted into the collections. 00:14.470 --> 00:16.170 So let's get started. 00:16.350 --> 00:21.550 So the query data from among mango bee collection you need to use the Mongo D-B find method. 00:21.560 --> 00:22.010 OK. 00:22.150 --> 00:29.530 So the find method is used to basically find as the name might suggest to find some documents inside 00:29.860 --> 00:33.130 the original collection that you put the documents in. 00:33.130 --> 00:40.790 So the basic syntax of the find function is to just do D-B dot collection underscore name so this is 00:40.870 --> 00:43.360 the collection name and then find. 00:43.490 --> 00:49.430 OK so your IDB for example dot my collection dot find. 00:49.480 --> 00:50.350 OK. 00:50.600 --> 00:54.310 Find so fully that that makes sense. 00:54.440 --> 00:59.560 And the find method will display all the documents in a non-structured way. 00:59.570 --> 01:00.460 So what does that mean. 01:00.470 --> 01:08.300 Well if you're right if we just do for example let's go back to my virtual machine and I have here my 01:08.300 --> 01:11.620 column has some a document inside. 01:11.660 --> 01:20.240 So if I say dvd my column does find and I just give it an empty document then you will find all the 01:20.240 --> 01:23.440 data and you'll notice that it looks very very jibberish. 01:23.450 --> 01:23.700 Right. 01:23.700 --> 01:26.090 It's very hard to read this. 01:26.090 --> 01:31.400 So since we don't want to you know you don't want to be debugging and trying to find where is the key 01:31.400 --> 01:36.290 that you're looking for and all that stuff than what we can do is to use the pretty function. 01:36.290 --> 01:38.340 So the Preedy function over here. 01:38.420 --> 01:44.550 So this pretty function over here makes whatever fine prints as the name might suggest printing. 01:44.630 --> 01:47.310 So it makes it look much much much more pretty. 01:47.330 --> 01:54.050 So you usually do D-B that might call up my collection that find and then once you have the results 01:54.050 --> 01:56.280 from find then you do not pretty. 01:56.360 --> 01:58.390 So you make it pretty. 01:58.430 --> 02:04.080 So if we go back here and you'll actually notice that I already did it before this Glasgow added to 02:04.270 --> 02:04.950 DBD. 02:04.970 --> 02:06.960 Michael I'm done fine. 02:07.220 --> 02:12.590 And then I'll give it an empty document and then not pretty. 02:12.740 --> 02:15.020 And then it will display the column just like that. 02:15.020 --> 02:20.570 So it shows you ID object title this description this and so on. 02:20.570 --> 02:25.850 So this is a very very much easier to debug than of course reading just having to read this and trying 02:25.850 --> 02:27.010 to debug. 02:27.020 --> 02:31.010 So that's just one point where many of us talking about. 02:31.010 --> 02:36.860 So apart from the find method there's also find one method and that returns only one document. 02:36.920 --> 02:43.080 So the form for the find function we're going to talk more about it the Find function we give it a door 02:43.330 --> 02:49.310 a document that this basically this document tells us what to what to search for. 02:49.310 --> 02:55.460 So let's say you have you want to search for all the customers whose names are let's say Jack. 02:55.580 --> 03:00.420 So you say name and then Jack. 03:00.570 --> 03:07.730 So maggoty would say for all the possible documents which have the name key with a jack value. 03:07.790 --> 03:08.350 OK. 03:08.540 --> 03:13.790 So but sometimes you might have more than one customer has yet you might have five or six jacks. 03:13.790 --> 03:14.280 Right. 03:14.420 --> 03:17.870 So in that case they're fine with return all of that. 03:18.030 --> 03:20.520 Whereas find one would only return one of them. 03:20.530 --> 03:25.820 So sometimes you don't just want one of them sees you find one or if you want to return all the set 03:25.820 --> 03:34.070 of possible documents that satisfy your search condition or your query condition then you would use 03:34.160 --> 03:36.350 just the normal find. 03:36.620 --> 03:42.160 Now for the query documents we have to pass through that to them document as I mentioned. 03:42.320 --> 03:43.660 And it's called a filter. 03:43.760 --> 03:51.800 So a filter is just a document and it should contain some information about what you expect their returned 03:51.950 --> 03:53.000 documents to have. 03:53.000 --> 03:56.580 So some conditions to satisfy that that are returned. 03:56.630 --> 04:02.570 So the query the document on the basis of some condition you can use the following operations so a bunch 04:02.570 --> 04:04.840 of operations that we'll talk about. 04:05.150 --> 04:06.700 So the first one is a quality. 04:06.710 --> 04:10.040 Let's say you want to return all the documents. 04:10.120 --> 04:14.180 Who's who's one of the keys matches one of the values. 04:14.210 --> 04:19.320 So you would do D-B for example that my column does find title. 04:19.340 --> 04:22.050 Mungo D-B overview not pretty. 04:22.100 --> 04:22.690 OK. 04:22.760 --> 04:31.010 So now you're specifying that you only want the records which have which which have which satisfy that 04:31.540 --> 04:37.270 the which satisfy that the title of them is man would be over. 04:37.370 --> 04:45.320 So if we go back here to our database or here and then I do D-B my collection that I find but then this 04:45.320 --> 04:47.980 time I pass it titled. 04:48.230 --> 04:55.410 And then two dots meaning I want the title to be mangled with the B over me. 04:55.610 --> 04:57.140 OK and I click enter. 04:57.350 --> 05:01.230 So that would show me that in the normal form but I want it to be pretty. 05:01.250 --> 05:04.380 So I do not pretty. 05:04.550 --> 05:09.860 And then it shows me here that this is the record that satisfies title longer D-B overview. 05:09.860 --> 05:16.580 Now if I chase this somehow right to be overviews just small letter you set up a capital letter then 05:16.580 --> 05:21.580 it would return nothing because none of the records in my column satisfy this search result. 05:21.590 --> 05:22.770 OK. 05:23.500 --> 05:31.010 There is also the less than OK so the less than is good as the name suggest you might want a key to 05:31.010 --> 05:34.040 have a value which is less than something right. 05:34.160 --> 05:42.350 So let's say you want to return all the records where the likes are less than 50 for example or less 05:42.350 --> 05:43.420 than something right. 05:43.580 --> 05:50.830 So you would do the meta find up do GBW my collection find and then the like. 05:51.510 --> 05:58.300 For the key and for the value you want to say I want this value to be less than 50 use this notation. 05:58.320 --> 05:59.750 So open parentheses. 05:59.810 --> 06:01.780 Open curly brackets. 06:01.830 --> 06:03.220 Dollar sign. 06:03.340 --> 06:10.910 LTE meaning less than and then 2.50 close curly brackets close curly brackets the outer one and then 06:10.900 --> 06:11.790 end up pretty. 06:11.790 --> 06:14.550 So let's try and let's try and do that. 06:14.580 --> 06:16.100 In our example. 06:16.170 --> 06:21.690 So if we go back here and then I want to find all the records with likes less than 50 so none of them 06:21.690 --> 06:25.270 right because there's only one record and it has 100 likes. 06:25.320 --> 06:26.160 But let's just try it. 06:26.160 --> 06:29.850 So if you do D-B dot my column that's fine. 06:30.390 --> 06:34.300 And then I want the record to have likes. 06:35.100 --> 06:41.110 And inside the lives I want I want it to have less than so I open a curly brackets. 06:41.160 --> 06:43.750 I do a dollar sign then LTE. 06:43.770 --> 06:44.890 So less then. 06:44.980 --> 06:51.440 And then two dots and then 50 Celeste click enter. 06:51.820 --> 06:53.070 And of course dot pretty. 06:53.070 --> 06:54.380 Of course. 06:55.240 --> 07:01.360 So you didn't get any results because of the only document in there has 100 likes which is more than 07:01.360 --> 07:02.120 50. 07:02.320 --> 07:09.430 But if if we instead replace the 50 was 200 for example then we would get again our record 1 on it because 07:09.430 --> 07:13.720 it satisfies the condition that the likes are less than 200 hundred hundreds. 07:13.750 --> 07:21.430 Less than two Okay now the third one the third operation that we can do is less than or equal do. 07:21.540 --> 07:24.020 So as you might have guessed it's key. 07:24.120 --> 07:25.590 And then LTE. 07:25.620 --> 07:27.070 So less than or equal. 07:27.120 --> 07:28.270 And then the value. 07:28.510 --> 07:33.060 So for example the need to find column that my column the find. 07:33.240 --> 07:38.730 So this one here only finds records which have less than strictly less than this one searches for less 07:38.730 --> 07:39.770 than or equal. 07:39.900 --> 07:40.570 OK. 07:40.890 --> 07:46.180 So give me my call got that find likes and less than or equal to 50 50. 07:46.230 --> 07:50.250 Let's go back and try to do this in our in our database. 07:50.450 --> 08:01.440 So if I go here and I do D-B my column find and then likes you if I say likes on and then I want it 08:01.440 --> 08:05.460 to be less than or equal to so dollar less than or equal to. 08:05.700 --> 08:14.420 And then the value is 50 and then duck for that I wouldn't have any records right. 08:14.460 --> 08:20.610 But if I changed this to 100 I want any record which has less than or equal to 100. 08:20.970 --> 08:23.210 Then I would get again this record over here. 08:23.220 --> 08:27.140 So this record has 100 which is less than or equal to 100. 08:27.150 --> 08:27.740 Right. 08:28.080 --> 08:28.590 OK. 08:28.740 --> 08:30.140 So let's move up. 08:31.930 --> 08:35.360 Now this the other ones are greater then. 08:35.380 --> 08:36.670 So it's key. 08:36.670 --> 08:45.610 Greater than GTY and then value and you would do it again divvied up my column find likes and 50 over 08:45.610 --> 08:46.120 here. 08:46.120 --> 08:47.990 So let's try to do that one too. 08:48.040 --> 08:54.550 So if you go back to our database and we do get beat up my call my collection does fine. 08:55.150 --> 09:03.340 And then for the likes I'm going to say likes and then for the value I want it to be Dollar greater 09:03.340 --> 09:05.910 than and 15. 09:06.120 --> 09:06.770 OK. 09:06.930 --> 09:08.780 And then pretty. 09:09.000 --> 09:13.580 So you get Again likes because this number of likes is more than 50. 09:13.650 --> 09:22.010 Now if I instead replace this 50 with 100 then I would get no records because this one is less than 09:22.010 --> 09:24.530 or equal to a hundred not greater than three. 09:24.860 --> 09:31.590 So it wouldn't be filtered now the first one is the greater than or equal. 09:31.690 --> 09:32.050 OK. 09:32.060 --> 09:37.160 So at least like there's less and less than or equal to there is greater then there is greater than 09:37.160 --> 09:39.410 or equal and it's GTY. 09:39.470 --> 09:42.410 OK so let's take an example again. 09:42.740 --> 09:48.560 Shouldn't be too different so we just we can just replace this year greater than or equal and that this 09:48.560 --> 09:53.180 time it will include this record over here because it's bigger than or equal to on. 09:53.240 --> 09:53.710 Right. 09:53.840 --> 09:58.420 So if it's bigger than or equal to a hundred then that's a valid. 09:58.770 --> 10:04.770 OK so little last filter that we can also pass or not the last one but one the last one. 10:04.770 --> 10:10.670 In these types of filters in the compares competitor filters are not equals. 10:10.680 --> 10:13.020 OK so they're not equals basically is. 10:13.040 --> 10:19.990 And so you're saying that I don't want to I want this key to be not equal to this value. 10:20.130 --> 10:26.850 So bring me all of that all the documents for example such that their name is not. 10:26.850 --> 10:28.360 For example Jack. 10:28.470 --> 10:29.170 OK. 10:29.580 --> 10:33.280 So I want all documents except the documents whose name is Jack. 10:33.400 --> 10:35.820 So you put here not equal to Jack. 10:35.820 --> 10:36.110 Right. 10:36.120 --> 10:37.230 And they are here. 10:37.400 --> 10:39.710 So let's take an example on right. 10:40.970 --> 10:48.590 On our database Frigo here and we choose not equal to so I don't want the likes to be equal to 100. 10:48.800 --> 10:54.380 So if I click enter then I wouldn't get any records right because none of the other records there's 10:54.380 --> 10:55.060 only one right. 10:55.130 --> 10:56.690 There's only one document right. 10:56.750 --> 11:00.850 None of the other documents have anything other than 100 likes. 11:01.070 --> 11:07.370 But if I put for example a hundred and one or a hundred and ten then there is one document which has 11:07.370 --> 11:11.090 likes not equal to 110 which is this one here. 11:11.510 --> 11:13.180 So hopefully this makes sense. 11:14.630 --> 11:15.000 OK. 11:15.000 --> 11:18.970 Another thing is that we can use and in in the in the filter. 11:19.080 --> 11:24.510 So you can for example you would if you if if your common with programming and you sometime you say 11:24.570 --> 11:32.620 if X is less than 10 and Y is bigger than 20 then do something right. 11:32.790 --> 11:38.130 So if I want to put this an operator here then I need to specify how I can do it. 11:38.150 --> 11:41.550 And the way we do it is we use the and operator. 11:41.550 --> 11:46.920 So you do dollar and and then we open up. 11:46.980 --> 11:48.450 And then two dots right. 11:48.600 --> 11:50.390 And then we open an array. 11:50.620 --> 11:54.140 And inside this array we have a tuple right. 11:54.240 --> 12:00.110 A bunch of documents that where I want the ends of all of these documents right. 12:00.120 --> 12:02.960 So I want this and this and this and and so on. 12:03.060 --> 12:03.540 OK. 12:03.660 --> 12:05.310 So for example here I can write. 12:05.310 --> 12:16.420 So this one my B likes and then let's see open parentheses. 12:16.440 --> 12:20.800 And then Dollar Sign greater than 50. 12:20.850 --> 12:23.630 So I want the likes to be greater than 50. 12:24.030 --> 12:35.230 And then here I can have but less than 100 right so I want the likes be Ltds less than and then a hundred 12:36.330 --> 12:43.560 so that way that means I'm searching for all the records where the likes are greater than 50 and the 12:43.560 --> 12:46.430 legs are less than. 12:46.480 --> 12:50.040 So LTE 100 less than 100 right. 12:50.070 --> 12:53.820 Sure remember here we have just in case you forget the letters there. 12:53.880 --> 12:57.720 LTE LTE G.T. ZTE and any. 12:57.840 --> 12:58.760 OK. 12:59.370 --> 13:04.710 So this search this would search for all of the posts where the likes are greater than 50 but less than 13:04.710 --> 13:05.320 a hundred. 13:05.370 --> 13:05.990 OK. 13:06.330 --> 13:09.380 So let's take an example of this in our database. 13:09.630 --> 13:17.670 So I want to search for all the posts with likes greater than 50 and less than or equal to 100. 13:17.700 --> 13:19.700 So this one would be included. 13:19.880 --> 13:20.540 OK. 13:20.550 --> 13:23.470 So I would do D-B got my collection. 13:23.550 --> 13:24.920 Not fine. 13:24.960 --> 13:25.600 Right. 13:25.860 --> 13:32.590 And then the first thing is I want to give it a document and inside this document I'm going to have 13:32.590 --> 13:42.160 a dollar and then two dots and then the the array signs on I'm sending get many conditions. 13:42.360 --> 13:45.470 So I have two conditions in this case right. 13:45.480 --> 13:51.010 The first condition is I want the number of likes to be. 13:51.210 --> 14:02.430 So to me to be greater than 50 and the second condition is I want the number of likes to be greater 14:02.430 --> 14:09.280 than a dollar and then less than or equal to and then 100. 14:09.280 --> 14:15.660 And then once I'm done with that then I prettify everything and I get this post because the number of 14:15.660 --> 14:17.760 likes is greater than 100. 14:17.780 --> 14:19.900 But less than or equal to 1. 14:20.220 --> 14:22.560 So this is satisfied pretty nice. 14:23.040 --> 14:24.110 So this is how you do it. 14:24.120 --> 14:26.320 And in Mungiki. 14:26.580 --> 14:27.910 Now if you want to do. 14:27.960 --> 14:29.150 Or statement. 14:29.190 --> 14:29.760 OK. 14:29.820 --> 14:36.140 So if you want to do an OR statement then we can also use a dollar or it's just like we use the dollar 14:36.160 --> 14:41.860 end so to query documents based on the condition you need to use the or keyword. 14:41.940 --> 14:46.810 Following is the basics syntax of or so this is an example it doing or. 14:46.830 --> 14:50.730 And then two dots and then open an array and inside of it. 14:50.850 --> 15:01.290 But many conditions so this is exactly like saying if x is equal to one or Y is equal to 1 rest of this 15:01.290 --> 15:03.250 is equal equal to 1. 15:03.420 --> 15:05.410 Then do something right. 15:05.970 --> 15:12.850 So this is saying if this is true in a document or if this is true in the document then add this document 15:12.850 --> 15:14.630 to the list that you will return to me. 15:14.640 --> 15:15.020 Right. 15:15.120 --> 15:19.870 So I want all the documents which satisfied one of these two conditions over here. 15:20.070 --> 15:20.660 OK. 15:20.970 --> 15:27.450 So let's take an example of this and this will be the final example that we take in this video so we 15:27.450 --> 15:28.720 will do DBD. 15:28.740 --> 15:31.140 My collection does fine. 15:31.320 --> 15:33.090 And so I want. 15:33.090 --> 15:40.000 So let's open of the document and that I want and or conditions so or. 15:40.380 --> 15:43.400 And then two dots and then an array. 15:43.740 --> 15:52.140 And inside this array I have two conditions that either one of them I want I want I like to be equal 15:52.140 --> 16:06.820 to I say 30 which is not true or I want the title to be Mungo D.B overview. 16:07.070 --> 16:07.990 OK. 16:08.260 --> 16:10.490 So I want the likes to be. 16:10.530 --> 16:12.950 Or the title to be Mangu with me over you. 16:13.120 --> 16:18.970 So I've tried prettify and we think that I should also get this record again because even though the 16:18.970 --> 16:26.500 lights are not 30 but the title is actually Mongo D-B overview so it counts in the records that satisfy 16:26.500 --> 16:28.180 either this one or this one. 16:28.180 --> 16:30.610 So it returns to me. 16:30.760 --> 16:33.550 So hopefully all of this makes sense. 16:33.820 --> 16:39.550 It just needs a little bit of practice to practice different and remember some of the keywords and also 16:39.550 --> 16:43.040 don't forget that sometimes people confuse the curly brackets. 16:43.210 --> 16:49.910 So these curly brackets are often various So there's always an outer curly bracket right. 16:49.930 --> 16:50.460 These ones. 16:50.460 --> 16:58.330 This one and this one after find and then after you open that or with that array there's a curly brackets 16:58.330 --> 17:05.710 inside and then sometimes for this value area here sometimes you have curly brackets and then Orphy 17:06.280 --> 17:07.960 or a greater than for example. 17:07.960 --> 17:13.060 So this is another curly bracket right so you just have to make sure you're you're inputting your curly 17:13.060 --> 17:16.000 brackets correctly so you don't miss anything. 17:16.570 --> 17:19.020 So yeah this will be it for this video. 17:19.120 --> 17:20.810 And until the next video. 17:20.920 --> 17:21.660 Happy go.