Take the help of $addToSet in MongoDB to specify a return format. Let us create a collection with documents −> db.demo207.insertOne({"FavouriteTechnology":"Spring Boot"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3d8e7a03d395bdc21346f1") } > db.demo207.insertOne({"FavouriteTechnology":"MongoDB"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3d8e8f03d395bdc21346f2") } > db.demo207.insertOne({"FavouriteTechnology":"Groovy"}); {    "acknowledged" : ... Read More

To determine if a specific value does not exist, use $ne in MongoDB. Let us create a collection with documents −> db.demo206.insertOne( ...   { ...      "ClientDetails": ...      [ ...         { ...            "Name":"Chris", ...       ... Read More

To count records on the basis of matching criteria, use count(). Let us create a collection with documents −> db.demo205.insertOne( ...   { ... ...      "id": "101", ...      "Name": "", ...      "Age": "", ...      "isActive": false ...   } ...); {   ... Read More

To display only an element found in an array, use aggregate(). Let us create a collection with documents −> db.demo204.insertOne( ...   { ...      "_id" : 101, ...      "Name" : "Chris", ...      "Age" : 23, ...      "details" : [ ...     ... Read More

To query nested array, use $elemMatch in MongoDB. Let us create a collection with documents −> db.demo203.insertOne({ ...   "_id" : "101", ...   "Name" : "Chris", ...   "details1" : [ ...      { ...         "empName" : "David", ...         "salary" ... Read More

For information on query plan, use explain() in MongoDB. Let us create a collection with documents −> db.demo202.insertOne({"StudentFirstName":"Chris", "StudentAge":21}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3c3bd103d395bdc21346e8") } > db.demo202.insertOne({"StudentFirstName":"David", "StudentAge":23}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3c3bd803d395bdc21346e9") } > db.demo202.insertOne({"StudentFirstName":"Bob", "StudentAge":22}); {    "acknowledged" : true, ... Read More

To update only a specific value, use update() and in that set the new value using $set. Let us create a collection with documents −> db.demo201.insertOne({"ClientName":"Chris Brown", "ClientAge":26}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3c39ca03d395bdc21346e5") } > db.demo201.insertOne({"ClientName":"David Miller", "ClientAge":35}); {    "acknowledged" : true,    "insertedId" : ... Read More

To filter multiple sub-documents in MongoDB, use aggregate(). Let us create a collection with documents −> db.demo200.insertOne( ...   { ...      "Id":"101", ...      "details1":[ ...         { ...            "isActive":true, ...            "SubjectName":"MySQL" ...   ... Read More

For aggregation in MongoDB, use aggregate(). Let us create a collection with documents −> db.demo199.insertOne( ...   { ...      "details1":{ ...         "details2":{ ...            "details3":{ ...               "Name":"Chris", ...           ... Read More

For this, use $pull along with update. Let us create a collection with documents −> db.demo198.insertOne({"List":{"Values":[10, 20, 30, 30, 70, 80, 90]}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3c224503d395bdc21346df") } > db.demo198.insertOne({"List":{"Values":[56, 978, 56, 34, 23, 34]}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3c225403d395bdc21346e0") } > ... Read More