Database Articles - Page 393 of 671

You can use below syntax for inserting an 8-byte integer in MongoDB through JavaScript shell −anyVariableName= {"yourFieldName" : new NumberLong("yourValue")};To display the above variable, you can use the variable name or printjson(). Following is the query to insert 8 byte integer in MongoDB −> userDetail = {"userId" : new NumberLong("98686869")}; { "userId" : NumberLong(98686869) }Let us display the above variable value using variable name. The query is as follows −> userDetailThis will produce the following output −{ "userId" : NumberLong(98686869) }Let us display the variable value using printjson() −> printjson(userDetail); This will produce the following output −{ "userId" : NumberLong(98686869) }

To access subdocument value, let us first create a collection with documents −> db.accessSubDocumentDemo.insertOne( ...    { ... ...       "Details" : { ...          "1" : { ...             "StudentLowerScore" : "33", ...             "StudentHoghScore" : "55" ...          }, ...          "2" : { ...             "StudentLowerScore" : "45", ...             "StudentHoghScore" : "65" ...          }, ...          "3" : ... Read More

You can use $pull operator. Let us first create a collection with documents −> db.pullAnArrayElementDemo.insertOne( { "StudentDetails": [ { "StudentFirstName":"Chris", "StudentScore":56 }, {"StudentFirstName":"Robert", "StudentScore":59 } ] } ); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd3b55bedc6604c74817cd5") }Following is the query to display all documents from a collection with the help of find() method −> db.pullAnArrayElementDemo.find().pretty();This will produce the following output −{    "_id" : ObjectId("5cd3b55bedc6604c74817cd5"),    "StudentDetails" : [       {          "StudentFirstName" : "Chris",          "StudentScore" : 56       },       {         ... Read More

You can use $match operator under aggregate() to get the first record. Let us first create a collection with documents −> db.conditionalFirstDemo.insertOne({_id:100, "StudentName":"Chris", "StudentSubject":null}); { "acknowledged" : true, "insertedId" : 100 } > db.conditionalFirstDemo.insertOne({_id:101, "StudentName":"Chris", "StudentSubject":null}); { "acknowledged" : true, "insertedId" : 101 } >db.conditionalFirstDemo.insertOne({_id:102, "StudentName":"Chris", "StudentSubject":"MongoDB"}); { "acknowledged" : true, "insertedId" : 102 } >db.conditionalFirstDemo.insertOne({_id:103, "StudentName":"Chris", "StudentSubject":"MongoDB"}); { "acknowledged" : true, "insertedId" : 103 } > db.conditionalFirstDemo.insertOne({_id:104, "StudentName":"Chris", "StudentSubject":null}); { "acknowledged" : true, "insertedId" : 104 }Following is the query to display all documents from a collection with the help of find() method −> db.conditionalFirstDemo.find();This will produce the following ... Read More

To create a collection correctly you need to use a MongoDB object in call i.e.db.createCollection("yourCollectionName");Let us implement the above syntax in order to create a collection and call it using a MongoDB object −> use sample; switched to db sample > db.createCollection("employeeInformation"); { "ok" : 1 }Display all the collections from the above ‘sample’ database −> db.getCollectionNames();This will produce the following output −[    "arraySizeErrorDemo",    "atleastOneMatchDemo",    "basicInformationDemo",    "combinedAndOrDemo",    "convertSQLQueryDemo",    "copyThisCollectionToSampleDatabaseDemo",    "countOrSizeDemo",    "distinctOnMultipleFieldsDemo",    "documentWithAParticularFieldValueDemo",    "employee",    "employeeInformation",    "findListOfIdsDemo",    "findMimimumElementInArrayDemo",    "findSubstring",    "getAllRecordsFromSourceCollectionDemo",    "getElementWithMaxIdDemo",    "insertDocumentWithDateDemo",    "internalArraySizeDemo", ... Read More

Let us first create a collection with documents −> db.embeddedDocumentDemo.insertOne( ...    { ...       "CustomerDetails":[ ...          {"CustomerName":"Chris", "CustomerPurchasePrice":3000}, ...          {"CustomerName":"Robert", "CustomerPurchasePrice":4500}, ...          {"CustomerName":"David", "CustomerPurchasePrice":1000}, ...       ] ...    } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd32347edc6604c74817ccd") }Following is the query to display all documents from a collection with the help of find() method −> db.embeddedDocumentDemo.find().pretty();This will produce the following output −{    "_id" : ObjectId("5cd32347edc6604c74817ccd"),    "CustomerDetails" : [       {          "CustomerName" ... Read More

Let us first create a collection with documents −> db.projectionAnElementDemo.insertOne( ...    { ...       "CustomerId":100, ...       "CustomerDetails": [ ...          { ...             "CustomerName": "Chris", ...             "CustomerCountryName": "US" ...          }, ...          { ...             "CustomerName": "Robert", ...             "CustomerCountryName": "UK" ...          } ...       ] ...    } ... ); {    "acknowledged" : true,   ... Read More

You can use $set operator for this. Let us first create a collection with documents −> db.updateSubObjectDemo.insertOne( ...    { ... ...       "ClientId" : 100, ...       "ClientDetails" : { ...          "ClientFirstName" : "Adam" ...       } ...    } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd31434b64f4b851c3a13e9") }Following is the query to display all documents from a collection with the help of find() method −> db.updateSubObjectDemo.find().pretty();This will produce the following output −{    "_id" : ObjectId("5cd31434b64f4b851c3a13e9"),    "ClientId" : 100,    "ClientDetails" : {   ... Read More

Let us first create a collection with a document −>db.replacingEntireDocumentDemo.insertOne({"StudentFirstName":"John", "StudentLastName":"Smith", "StudentCountryName":"US"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd3119bb64f4b851c3a13e8") }Following is the query to display document from a collection with the help of find() method −> db.replacingEntireDocumentDemo.find().pretty();This will produce the following output −{    "_id" : ObjectId("5cd3119bb64f4b851c3a13e8"),    "StudentFirstName" : "John",    "StudentLastName" : "Smith",    "StudentCountryName" : "US" }Following is the query to update a MongoDB document while replacing the entire document −>db.replacingEntireDocumentDemo.update({"StudentFirstName":"John", "StudentLastName":"Smith", "StudentCountryName":"US"}, {"StudentFirstName":"David", "StudentLastName":"Miller", "StudentCountryName":"AUS"}); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })Let us display all the records from the collection ... Read More

Use unique and set it to TRUE. Let us implement the same by creating index and setting two columns to unique −>db.keepTwoColumnsUniqueDemo.createIndex({"StudentFirstName":1, "StudentLastName":1}, {unique:true}); {    "createdCollectionAutomatically" : true,    "numIndexesBefore" : 1,    "numIndexesAfter" : 2,    "ok" : 1 }Now you can insert documents in the above collection −>db.keepTwoColumnsUniqueDemo.insertOne({"StudentFirstName":"John", "StudentLastName":"Smith", "StudentAge":21}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd30fd7b64f4b851c3a13e5") } >db.keepTwoColumnsUniqueDemo.insertOne({"StudentFirstName":"John", "StudentLastName":"Doe", "StudentAge":23}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd30fe5b64f4b851c3a13e6") } >db.keepTwoColumnsUniqueDemo.insertOne({"StudentFirstName":"John", "StudentLastName":"Smith", "StudentAge":24}); 2019-05-08T22:50:42.803+0530 E QUERY [js] WriteError: E11000 duplicate key error collection: sample.keepTwoColumnsUniqueDemo index: StudentFirstName_1_StudentLastName_1 dup key: { : "John", : "Smith" } ... Read More