Use $unwind twice for specific embedded document in MongoDB. Let us create a collection with documents −> db.demo631.insert( ...    { ...       id: "101", ...       Info1: [ ...          { ...             CountryName : "US", ...             Info2 : [ ...                { ...                   Name:"Chris", ...                   Age:24 ...                }, { ... Read More

To sort documents, use sort() along with find(). Let us create a collection with documents −> db.demo630.insertOne({"Value":10}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9b080e6c954c74be91e6ba") } > db.demo630.insertOne({"Value":200}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9b08116c954c74be91e6bb") } > db.demo630.insertOne({"Value":40}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9b08146c954c74be91e6bc") } > db.demo630.insertOne({"Value":60}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9b08176c954c74be91e6bd") }Display all documents from a collection with the help of find() method −> db.demo630.find();This will produce the following output −{ "_id" : ObjectId("5e9b080e6c954c74be91e6ba"), "Value" : 10 } { "_id" : ObjectId("5e9b08116c954c74be91e6bb"), "Value" : 200 } { "_id" : ... Read More

You can use $match. The $match filters the documents to pass only the documents that match the specified condition to the next pipeline stage. Let us create a collection with documents −> db.demo629.insertOne( ...    { ... ...       "Subject": [ ...          "MySQL", ...          "MongoDB" ...       ], ...       "details": [ ...          { ...             Name:"Chris", ...             "Marks":78 ...          }, ...          { ... Read More

To query for values in list, use positional operator($) in MongoDB. Let us create a collection with documents −> db.demo628.insertOne({id:1, Name:["Chris", "David", "John"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9ae7ea6c954c74be91e6b6") } > db.demo628.insertOne({id:1, Name:["Carol", "Sam"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9ae7f26c954c74be91e6b7") } > db.demo628.insertOne({id:2, Name:["Mike", "Sam", "John"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9ae8056c954c74be91e6b8") }Display all documents from a collection with the help of find() method −> db.demo628.find();This will produce the following output −{ "_id" : ObjectId("5e9ae7ea6c954c74be91e6b6"), "id" : 1, "Name" : [ "Chris", "David", "John" ] } { "_id" : ObjectId("5e9ae7f26c954c74be91e6b7"), "id" ... Read More

For this, use aggregate() along with $group. Let us create a collection with documents −> db.demo627.insertOne({id:101, "Name":"Chris", "Marks":54}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9acb306c954c74be91e6b2") } > db.demo627.insertOne({id:102, "Name":"Bob", "Marks":74}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9acb3c6c954c74be91e6b3") } > db.demo627.insertOne({id:101, "Name":"Chris", "Marks":87}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9acb426c954c74be91e6b4") } > db.demo627.insertOne({id:102, "Name":"Mike", "Marks":70}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9acb4b6c954c74be91e6b5") }Display all documents from a collection with the help of find() method −> db.demo627.find();This will produce the following output −{ "_id" : ObjectId("5e9acb306c954c74be91e6b2"), "id" : 101, "Name" : "Chris", "Marks" : ... Read More

Remove document using remove(), whose value is matched with $eq from a MongoDB collection. The $eq operator matches documents where the value of a field equals the specified value.Let us create a collection with documents −> db.demo626.insertOne({id:1, "Name":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9ac6376c954c74be91e6ae") } > db.demo626.insertOne({id:2, "Name":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9ac63e6c954c74be91e6af") } > db.demo626.insertOne({id:3, "Name":"Bob"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9ac6436c954c74be91e6b0") } > db.demo626.insertOne({id:4, "Name":"Mike"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9ac6486c954c74be91e6b1") }Display all documents from a collection with the help of find() method −> db.demo626.find();This ... Read More

For array interection in MongoDB, use the $setIntersection in aggregate(). Let us create a collection with documents −> db.demo625.insertOne( ...    { ...       Name: "John", ...       Marks: [56, 98, 60] ...    } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9ab8e16c954c74be91e6aa") } > db.demo625.insertOne( ...    { ...       Name: "John", ...       Marks: [110, 56, 72] ...    } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9ab8e26c954c74be91e6ab") } > db.demo625.insertOne( ...    { ...       Name: "Chris", ...       ... Read More

For all elements of a field in MongoDB, use find() and in that, use $elemMatch. The $elemMatch operator matches documents that contain an array field with at least one element that matches all the specified query criteria.Let us create a collection with documents −> db.demo624.insertOne({"ListOfName":["John", "Chris", "David", "Bob"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9ab3ff6c954c74be91e6a5") } > db.demo624.insertOne({"ListOfName":["John", "Chris"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9ab4026c954c74be91e6a6") } > db.demo624.insertOne({"ListOfName":["John", "Chris", "Carol"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9ab4076c954c74be91e6a7") } > db.demo624.insertOne({"ListOfName":["John", "Chris", "Bob"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e9ab40e6c954c74be91e6a8") } > ... Read More

Yes, to search an array of objects, use $unwind in MongoDB aggregate(). To match, use $match. Let us create a collection with documents −> db.demo623.insertOne( ...    { ...       _id:1, ...       details:[ ...          { ...             Name:"Chris" ...          }, ...          { ...             DueDate:new ISODate("2020-01-10") ...          }, ...          { ...             CountryName:"US" ...          } ... ... Read More

Yes, you can use ensureIndex(). MongoDB provides complete support for indexes on any field in a collection of documents.Let us create a collection with documents −> db.demo622.ensureIndex({_id:1, Name:1, Age:1}); {    "createdCollectionAutomatically" : true,    "numIndexesBefore" : 1,    "numIndexesAfter" : 2,    "ok" : 1 } > db.demo622.insertOne({_id:101, Name:"Chris", Age:21}); { "acknowledged" : true, "insertedId" : 101 } > db.demo622.insertOne({_id:102, Name:"Chris", Age:22}); { "acknowledged" : true, "insertedId" : 102 } > db.demo622.insertOne({_id:103, Name:"Bob", Age:21}); { "acknowledged" : true, "insertedId" : 103 } > db.demo622.insertOne({_id:104, Name:"Chris", Age:22}); { "acknowledged" : true, "insertedId" : 104 } > db.demo622.insertOne({_id:104, Name:"Chris", Age:22}); 2020-04-18T12:21:18.085+0530 ... Read More