To find MongoDB based on a condition, use find() and set the condition. Let us create a collection with documents −> db.demo708.insertOne({"Name":"John", Marks:54}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea702e4d346dcb074dc6f33") } > db.demo708.insertOne({"Name":"Chris", Marks:35}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea702e6d346dcb074dc6f34") } > db.demo708.insertOne({"Name":"David", Marks:45}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea702ebd346dcb074dc6f35") } > db.demo708.insertOne({"Name":"Bob", Marks:40}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea702fad346dcb074dc6f36") }Display all documents from a collection with the help of find() method −> db.demo708.find();This will produce the following output −{ "_id" : ObjectId("5ea702e4d346dcb074dc6f33"), "Name" : "John", "Marks" : 54 ... Read More

Let us create a collection with documents −> db.demo707.insertOne( ...    { ...       id:101, ...       "serverInformation": ...       [ ...          { ...             "IP":"192.56.34.3", ...             "Status":"Active" ...          }, ...          { ...             "IP":"192.56.36.4", ...             "Status":"Inactive" ...          } ...       ] ...    } ... ); {    "acknowledged" : true,     ... Read More

Following is the syntax showing document and subdocument −db.yourCollectionName.insertOne(    {       yourFiledName:yourValue,       yourFieldName : [          {             yourFiledName1,             yourFiledName2,             .             .             .             N          }       ]    } );Let us see an example create a collection with documents −> db.demo706.insertOne( ...    { ...       PortalName: "GameApplication", ... Read More

To query embedded documents in MongoDB, use aggregate(). Let us create a collection with documents −> db.demo705.insertOne( ...    { ...       _id:101, ...       "Information": ...       [ ...          { ...             "StudentName":"Chris", ...             "StudentAge":21 ...          }, ...          { ...             "StudentName":"David", ...             "StudentAge":23 ...          }, ...          { ...     ... Read More

To get unique values and ignore duplicates, use distinct() in MongoDB. The distinct() finds the distinct values for a specified field across a single collection and returns the results in an array.Let us create a collection with documents −> db.demo704.insertOne({"LanguageCode":"hi"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6ee18551299a9f98c93bd") } > db.demo704.insertOne({"LanguageCode":"en"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6ee1e551299a9f98c93be") } > db.demo704.insertOne({"LanguageCode":"hi"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6ee20551299a9f98c93bf") } > db.demo704.insertOne({"LanguageCode":"eo"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6ee2c551299a9f98c93c0") } > db.demo704.insertOne({"LanguageCode":"eu"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6ee2f551299a9f98c93c1") } > db.demo704.insertOne({"LanguageCode":"fo"}); ... Read More

To count the number of array items in a document, use $size in MongoDB. Let us create a collection with documents −> db.demo703.insertOne({"ListOfSubject":["MySQL", "MongoDB"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6ebaf551299a9f98c93b4") } > db.demo703.insertOne({"ListOfSubject":["Java"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6ebb5551299a9f98c93b5") } > db.demo703.insertOne({"ListOfSubject":["C", "C++", "Python"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6ebbf551299a9f98c93b6") }Display all documents from a collection with the help of find() method −> db.demo703.find();This will produce the following output −{ "_id" : ObjectId("5ea6ebaf551299a9f98c93b4"), "ListOfSubject" : [ "MySQL", "MongoDB" ] } { "_id" : ObjectId("5ea6ebb5551299a9f98c93b5"), "ListOfSubject" : [ "Java" ] } { ... Read More

To create index, use createIndex() in MongoDB. Let us create a collection with documents −> db.demo702.createIndex({"details.id":1}); {    "createdCollectionAutomatically" : true,    "numIndexesBefore" : 1,    "numIndexesAfter" : 2,    "ok" : 1 } > db.demo702.insertOne({ ...    "details" : [ ...       { ...          id:101, ...          studentInfo:{ ...             "StudentName" : "Chris", ...             "StudentAge" : 23, ...          } ...       }, ...    { ... ...       id: 102, ...       studentInfo:{ ...          "StudentName" : "Robert", ...          "StudentAge" : 20, ...       } ...    } ... ] ... } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6ea3b551299a9f98c93b3") }Display all documents from a collection with the help of find() method −> db.demo702.find().pretty();This will produce the following output −{    "_id" : ObjectId("5ea6ea3b551299a9f98c93b3"),    "details" : [       {          "id" : 101,          "studentInfo" : {             "StudentName" : "Chris",             "StudentAge" : 23          }       },       {          "id" : 102,          "studentInfo" : {             "StudentName" : "Robert",             "StudentAge" : 20          }       }    ] }

You can 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.demo701.insertOne({"ListOfValues":[100, 200, 300]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6e8cf551299a9f98c93b0") } > db.demo701.insertOne({"ListOfValues":[500, 700, 1000]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6e8d8551299a9f98c93b1") } > db.demo701.insertOne({"ListOfValues":[300, 350, 450]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6e8e1551299a9f98c93b2") }Display all documents from a collection with the help of find() method −> db.demo701.find();This will produce the following output −{ "_id" : ObjectId("5ea6e8cf551299a9f98c93b0"), "ListOfValues" : [ 100, ... Read More

For this, use $regex in MongoDB. We will search for document field value with name “David”, irrespective of case. Let us create a collection with documents −> db.demo700.insertOne( { details: [ { Name:"david" }]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6e6b1551299a9f98c93ac") } > db.demo700.insertOne( { details: [ { Name:"Chris" }]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6e6b9551299a9f98c93ad") } > db.demo700.insertOne( { details: [ { Name:"DAVID" }]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6e6bf551299a9f98c93ae") } > db.demo700.insertOne( { details: [ { Name:"David" }]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6e6c4551299a9f98c93af") }Display all documents ... Read More

For multiple atomic updates, use update() along with $set. Let us create a collection with documents −> db.demo699.insertOne({Name:"Chris Brown"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6e370551299a9f98c93a7") } > db.demo699.insertOne({Name:"David Miller"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6e37a551299a9f98c93a8") } > db.demo699.insertOne({Name:"Chris Brown"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6e381551299a9f98c93a9") } > db.demo699.insertOne({Name:"John Doe"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5ea6e38a551299a9f98c93aa") }Display all documents from a collection with the help of find() method −> db.demo699.find();This will produce the following output −{ "_id" : ObjectId("5ea6e370551299a9f98c93a7"), "Name" : "Chris Brown" } { "_id" : ObjectId("5ea6e37a551299a9f98c93a8"), "Name" ... Read More