1 00:00:01,220 --> 00:00:02,299 ‫Finally, let's learn 2 00:00:02,299 --> 00:00:05,463 ‫how to delete documents in MongoDB. 3 00:00:06,790 --> 00:00:08,160 ‫So just like before, 4 00:00:08,160 --> 00:00:11,641 ‫we have delete one to delete one single document, 5 00:00:11,641 --> 00:00:14,290 ‫and we have delete many, well, 6 00:00:14,290 --> 00:00:17,430 ‫to delete multiple documents at the same time. 7 00:00:17,430 --> 00:00:19,430 ‫Alright, and just like before, 8 00:00:19,430 --> 00:00:21,250 ‫delete one will only work 9 00:00:21,250 --> 00:00:24,220 ‫for the first document matching your query. 10 00:00:24,220 --> 00:00:25,800 ‫And delete many will of course 11 00:00:25,800 --> 00:00:28,600 ‫work for all the documents matching your query. 12 00:00:28,600 --> 00:00:29,796 ‫Okay. 13 00:00:29,796 --> 00:00:33,660 ‫Just to get an overview of what we have here 14 00:00:33,660 --> 00:00:35,890 ‫at this moment in time, 15 00:00:35,890 --> 00:00:39,760 ‫let's do a find of all the tours. 16 00:00:39,760 --> 00:00:40,830 ‫And what I'm gonna do now 17 00:00:40,830 --> 00:00:42,330 ‫is to delete all the tours 18 00:00:42,330 --> 00:00:44,923 ‫which have a rating less than 4.8. 19 00:00:45,987 --> 00:00:48,172 ‫So that's gonna be just the first one 20 00:00:48,172 --> 00:00:51,491 ‫but if we had multiple tours with that condition, 21 00:00:51,491 --> 00:00:54,030 ‫then all of them would be deleted. 22 00:00:54,030 --> 00:00:57,050 ‫So db.tours.deleteMany. 23 00:01:01,843 --> 00:01:04,260 ‫So the condition is rating... 24 00:01:06,750 --> 00:01:08,460 ‫Open a new object 25 00:01:08,460 --> 00:01:13,460 ‫so that we can use the less than operator and 4.8. 26 00:01:13,680 --> 00:01:17,500 ‫Close it and then close this one. 27 00:01:17,500 --> 00:01:22,040 ‫And run this and here we see that it's deleted one document. 28 00:01:22,040 --> 00:01:23,620 ‫Right away it's telling us here 29 00:01:23,620 --> 00:01:26,573 ‫how many documents were affected by this operation. 30 00:01:27,440 --> 00:01:29,240 ‫So if we do this find now, 31 00:01:29,240 --> 00:01:32,680 ‫well then the first one that we had is gone. 32 00:01:32,680 --> 00:01:34,610 ‫Alright, so that's no problem. 33 00:01:34,610 --> 00:01:37,637 ‫We are only really using this here to play around 34 00:01:37,637 --> 00:01:40,640 ‫and so we can delete as much as we want here. 35 00:01:40,640 --> 00:01:41,760 ‫No problem. 36 00:01:41,760 --> 00:01:42,980 ‫Now if you wanna delete 37 00:01:42,980 --> 00:01:45,180 ‫all of the documents in the collection, 38 00:01:45,180 --> 00:01:46,543 ‫you would do it like this. 39 00:01:48,920 --> 00:01:50,818 ‫So deleteMany. 40 00:01:50,818 --> 00:01:52,360 ‫And I'm not gonna execute this. 41 00:01:52,360 --> 00:01:54,130 ‫But you would do it like this. 42 00:01:54,130 --> 00:01:57,059 ‫So all you have to do is pass in the empty object 43 00:01:57,059 --> 00:02:00,280 ‫because the empty object is basically a condition 44 00:02:00,280 --> 00:02:03,196 ‫that all of the documents always match. 45 00:02:03,196 --> 00:02:08,143 ‫It would be like simply using an empty object here in find. 46 00:02:09,223 --> 00:02:11,225 ‫I'm not gonna do that 47 00:02:11,225 --> 00:02:13,393 ‫and you should be careful with it, 48 00:02:13,393 --> 00:02:16,760 ‫especially when doing it in a real app 49 00:02:16,760 --> 00:02:19,690 ‫because you cannot come back from this operation. 50 00:02:19,690 --> 00:02:21,580 ‫So unless you have some backup in place, 51 00:02:21,580 --> 00:02:23,686 ‫this will effectively delete all the documents 52 00:02:23,686 --> 00:02:25,350 ‫in your collection, 53 00:02:25,350 --> 00:02:27,170 ‫in this case the tours collection. 54 00:02:27,170 --> 00:02:29,460 ‫So I'm not performing that. 55 00:02:29,460 --> 00:02:30,730 ‫I just wanted to show you 56 00:02:30,730 --> 00:02:32,810 ‫that this is how we delete everything. 57 00:02:32,810 --> 00:02:34,440 ‫So this is the simplest operation 58 00:02:34,440 --> 00:02:36,450 ‫and we don't use it all that often. 59 00:02:36,450 --> 00:02:38,740 ‫But I just wanted to have a short video 60 00:02:38,740 --> 00:02:41,383 ‫just to demonstrate that it also exists.