Found 1359 Articles for MongoDB

To clear console in MongoDB, you can use any of the following two syntaxes.The first syntax is as follows, which is the usage of keyboard shortcut −Ctrl + LAfter pressing the above key, you can clear console in MongoDB.The second syntax is as follows −clsTo understand the above syntaxes, let us implement them one by one. Here is the snapshot of my console.The first query is as follows to clear console in MongoDB −Ctrl+L;The following is the output −Look at the above sample output, the console has been cleared. Let us check the console once again.The second query is as ... Read More

You can use $pull operator to remove the object from an array in MongoDB. To understand the concept, let us create a collection with the document. The query to create a collection with a document is as follows −> db.removeObjectFromArrayDemo.insertOne( ... {    ...    ... "StudentName": "John",    ... "StudentAcademicProjectDetails":    ... [{          ... "StudentProjectId": 101,          ... "StudentProjectName": "Pig Dice Game"       ... },       ... {          ... "StudentProjectId": 110,          ... "StudentProjectName": "Library Management System"       ... ... Read More

MongoDB indexes every value of an array so that you can query for single elements.To understand the concept, let us create a collection with the document. The query to create a collection with a document is as follows −> db.indexingForArrayElementDemo.insertOne({"StudentFavouriteSubject":["MongoDB", "MySQL"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8acdca6cea1f28b7aa0816") }Display all documents from a collection with the help of find() method. The query is as follows −> db.indexingForArrayElementDemo.find().pretty();The following is the output −{    "_id" : ObjectId("5c8acdca6cea1f28b7aa0816"),    "StudentFavouriteSubject" : [       "MongoDB",       "MySQL"    ] }Here is the query by which MongoDB index ... Read More

Let us first create a collection with the document. The query to create a collection with a document is as follows −> db.aggregationFrameworkWithOrMatchDemo.insertOne({"StudentFirstName":"John",    "StudentLastName":"Smith", "StudentAge":23}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ac3a96cea1f28b7aa080d") } > db.aggregationFrameworkWithOrMatchDemo.insertOne({"StudentFirstName":"Carol",    "StudentLastName":"Tayor", "StudentAge":24}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ac3bc6cea1f28b7aa080e") } > db.aggregationFrameworkWithOrMatchDemo.insertOne({"StudentFirstName":"David",    "StudentLastName":"Miller", "StudentAge":21}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ac3ce6cea1f28b7aa080f") } > db.aggregationFrameworkWithOrMatchDemo.insertOne({"StudentFirstName":"Bob",    "StudentLastName":"Taylor", "StudentAge":20}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ac3e16cea1f28b7aa0810") } > db.aggregationFrameworkWithOrMatchDemo.insertOne({"StudentFirstName":"Robert",    "StudentLastName":"Smith", "StudentAge":20}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ac3fb6cea1f28b7aa0811") } > db.aggregationFrameworkWithOrMatchDemo.insertOne({"StudentFirstName":"Mike",    "StudentLastName":"Miller", ... Read More

To query condition on comparing 2 fields, use the following syntax −db.yourCollectionName.find( { $where: function() { return this.yourFirstFieldName < this.yourSecondFieldName } } ).pretty();To understand the syntax, let us create a collection with the document. The query to create a collection with a document is as follows −> db.comparingTwoFieldsDemo.insertOne({"StudentName":"John", "StudentAge":21, "StudentMathMarks":99, "StudentPhysicsMarks":98}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ac09e6cea1f28b7aa0807") } > db.comparingTwoFieldsDemo.insertOne({"StudentName":"Carol", "StudentAge":22, "StudentMathMarks":79, "StudentPhysicsMarks":89}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ac0b46cea1f28b7aa0808") } > db.comparingTwoFieldsDemo.insertOne({"StudentName":"David", "StudentAge":24, "StudentMathMarks":39, "StudentPhysicsMarks":45}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8ac0c96cea1f28b7aa0809") } > db.comparingTwoFieldsDemo.insertOne({"StudentName":"Bob", "StudentAge":23, "StudentMathMarks":87, "StudentPhysicsMarks":78}); {    "acknowledged" : ... Read More

You can remove an array element by its index using the following two steps −The first step is as follows −db.yourCollectionName.update({}, {$unset : {"yourArrayFieldName.yourIndexValue" : 1 }});The above syntax will put a null value at the location of ‘yourIndexValue’. After that, you need to pull the null value from array filed to remove from an array element.The second step is as follows −db.yourCollectionName.update({}, {$pull : {"yourArrayFieldName" : null}});To implement the syntax, let us create a collection with the document. The query to create a collection with a document is as follows −> db.removeArrayElementByItsIndexDemo.insertOne({"InstructorName":"David",    "InstructorAge":28, "InstructorSubject":["MongoDB", "MySQL", "Java", "SQL Server", ... Read More

Let us work around two cases −Case 1 − The syntax is as follows when the field is present and set to null.db.yourCollectionName.count({yourFieldName: null});Case 1 − The syntax is as follows when the field is not present and not set.db.yourCollectionName.count({yourFieldName: {$exists: false}});To understand both the above syntaxes, let us create a collection with the document. The query to create a collection with a document is as follows −> db.fieldIsNullOrNotSetDemo.insertOne({"EmployeeName":"Larry", "EmployeeAge":null, "EmployeeSalary":18500}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8a995c6cea1f28b7aa07fe") } > db.fieldIsNullOrNotSetDemo.insertOne({"EmployeeName":"Bob", "EmployeeAge":21, "EmployeeSalary":23500}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8a99836cea1f28b7aa07ff") } > db.fieldIsNullOrNotSetDemo.insertOne({"EmployeeName":"Carol", "EmployeeSalary":45500}); { ... Read More

To find items that do not have a certain field, use the $exists operator. The syntax is as follows −> db.yourCollectionName.find({"yourItemName":{$exists:false}}).pretty();To understand the syntax, let us create a collection with the document. The query to create a collection with a document is as follows −> db.findDocumentDoNotHaveCertainFields.insertOne({"UserId":101, "UserName":"John", "UserAge":21}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8a95fb6cea1f28b7aa07fb") } > db.findDocumentDoNotHaveCertainFields.insertOne({"UserName":"David", "UserAge":22, "UserFavouriteSubject":["C", "Java"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8a96116cea1f28b7aa07fc") } > db.findDocumentDoNotHaveCertainFields.insertOne({"UserName":"Bob", "UserAge":24, "UserFavouriteSubject":["MongoDB", "MySQL"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8a96306cea1f28b7aa07fd") }Display all documents from a collection with the help of find() method. The ... Read More

PyMongo is a Python distribution containing tools for working with MongoDB. To perform regex queries with PyMongo, the syntax is as follows −db.yourCollectionName.find({'yourCollectionName':{'$regex':'^yourWords'}}).pretty();The above syntax will give all those documents that start from a specific word.To understand the syntax, let us create a collection with the document. The query to create a collection with a document is as follows −> db.performRegex.insertOne({"ClientName":"Larry", "ClientFolderInformation":[    "Folder 1", "Folder 2", "Folder 3", "Folder 4", "Folder 5"], "MainFolderLocation":"/MainFolder/Details/ClientFolder" }); {    "acknowledged" : true,    "insertedId" : ObjectId("5c8a8b186cea1f28b7aa07f2") } > db.performRegex.insertOne({"ClientName":"Larry", "ClientFolderInformation":[    "ClientFolder 1", "ClientFolder 2", "ClientFolder 3", "ClientFolder 4", "ClientFolder 5"],   ... Read More

Both the getUsers() method and SHOW command can be used to list all users in the Mongo shell.Case 1 − Using getUsers()The syntax is as follows −db.getUsers();Case 2 − Using show commandThe syntax is as follows −show users;Let us implement both the syntaxes in order to list all users in the Mongo shell.Case 1 − The first query is as follows −> db.getUsers();The following is the output −[    {       "_id" : "test.John",       "user" : "John",       "db" : "test",       "roles" : [          {   ... Read More