To convert numeric string to number, use parseInt() in MongoDB. Let us create a collection with documents −> db.demo208.insertOne( { "value":"50"} ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3d92d803d395bdc21346f6") } > db.demo208.insertOne( { "value":"2350"} ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3d92dd03d395bdc21346f7") }Display all documents from a collection with the help of find() method −> db.demo208.find();This will produce the following output −{ "_id" : ObjectId("5e3d92d803d395bdc21346f6"), "value" : "50" } { "_id" : ObjectId("5e3d92dd03d395bdc21346f7"), "value" : "2350" }Following is the query to convert numeric string to number −> db.demo208.find().forEach( function (doc) { ...   doc.value = parseInt(doc.value); ... Read More

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" : true,    "insertedId" : ObjectId("5e3d8ea603d395bdc21346f3") }Display all documents from a collection with the help of find() method −> db.demo207.find();This will produce the following output −{ "_id" : ObjectId("5e3d8e7a03d395bdc21346f1"), "FavouriteTechnology" : "Spring Boot" } { "_id" : ObjectId("5e3d8e8f03d395bdc21346f2"), "FavouriteTechnology" : "MongoDB" } { "_id" : ObjectId("5e3d8ea603d395bdc21346f3"), "FavouriteTechnology" : "Groovy" }Following is ... 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", ...            "Age":28, ...            "CountryName":"US" ...         } ...      ] ...   } ...); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3d8bd403d395bdc21346ee") } > db.demo206.insertOne( ...   { ...      "ClientDetails": ...      [ ...     ... 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 ...   } ...); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3d8a3003d395bdc21346eb") } > db.demo205.insertOne( ...   { ... ...      "id": "102", ...      "Name": "Chris", ...      "Age": "25", ...      "isActive": true ...   } ...); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3d8a3003d395bdc21346ec") } > db.demo205.insertOne( ... 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" : [ ...         { ...            "id" : "1001", ...            "empId" : "John_1001", ...            "salary" : "50000", ...            "Technology" : "Java" ...         }, ...         ... 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" : "50000", ...         "technology" : [ ...            "MySQL", ...            "MongoDB" ...         ] ...      }, ...      { ...         "empName" : "Carol", ...       ... 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,    "insertedId" : ObjectId("5e3c3bde03d395bdc21346ea") }Display all documents from a collection with the help of find() method −> db.demo202.find();This will produce the following output −{ "_id" : ObjectId("5e3c3bd103d395bdc21346e8"), "StudentFirstName" : "Chris", "StudentAge" : 21 } { "_id" : ObjectId("5e3c3bd803d395bdc21346e9"), "StudentFirstName" : "David", "StudentAge" : 23 } { "_id" : ObjectId("5e3c3bde03d395bdc21346ea"), "StudentFirstName" ... 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" : ObjectId("5e3c39d403d395bdc21346e6") } > db.demo201.insertOne({"ClientName":"Carol Taylor", "ClientAge":28}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3c39e603d395bdc21346e7") }Display all documents from a collection with the help of find() method −> db.demo201.find();This will produce the following output −{ "_id" : ObjectId("5e3c39ca03d395bdc21346e5"), "ClientName" : "Chris Brown", "ClientAge" : 26 } { "_id" : ObjectId("5e3c39d403d395bdc21346e6"), ... 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" ...         }, { ...            "isActive":false, ...            "SubjectName":"Java" ...         } ...      ], ...      "details2":[ ...         { ...            "isActive":false, ...     ... Read More

For aggregation in MongoDB, use aggregate(). Let us create a collection with documents −> db.demo199.insertOne( ...   { ...      "details1":{ ...         "details2":{ ...            "details3":{ ...               "Name":"Chris", ...               "details4":{ ...                  "details5":{ ...                     "v1":10, ...                     "v2":20, ...                     "v3":30 ... ... Read More