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Found 6702 Articles for Database
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
243 Views
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
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
635 Views
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
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
296 Views
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
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
199 Views
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
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
382 Views
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
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
226 Views
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
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
268 Views
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") } > db.demo198.insertOne({"List":{"Values":[21, 12, 14, 15, 34, 56]}}); { "acknowledged" : true, "insertedId" : ObjectId("5e3c226603d395bdc21346e1") }Display all documents from a collection with the help of find() method −> db.demo198.find();This will produce the following output −{ "_id" : ObjectId("5e3c224503d395bdc21346df"), "List" : { "Values" : [ 10, 20, 30, 30, 70, 80, ... Read More
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
79 Views
No, using LIMIT() decreases the bandwidth consumption and it does not increase query speed. Let us see an example and create a collection with documents −> db.demo197.insertOne({"Name":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3afde803d395bdc21346d8") } > db.demo197.insertOne({"Name":"Bob"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3afdef03d395bdc21346d9") } > db.demo197.insertOne({"Name":"David"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3afdf203d395bdc21346da") } > db.demo197.insertOne({"Name":"Sam"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3afdf603d395bdc21346db") } > db.demo197.insertOne({"Name":"Mike"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3afdf903d395bdc21346dc") } > db.demo197.insertOne({"Name":"Carol"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3afe1603d395bdc21346dd") } > db.demo197.insertOne({"Name":"John"}); { ... Read More
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
438 Views
Let us create a collection with documents −> db.demo196.insertOne( ... { ... ... "Id" : "101", ... "details" : [ ... { ... "FirstName" : "Chris", ... "LastName" : "Brown", ... "Score" : 45 ... }, ... { ... "FirstName" : "David", ... "LastName" : "Miller", ... "Score" : 87 ... ... Read More
![AmitDiwan](https://www.tutorialspoint.com/assets/profiles/123055/profile/60_187394-1565938756.jpg)
328 Views
To return a list of specific values, use map(). Let us create a collection with documents −> db.demo195.insertOne({"Subject":"MySQL"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3af3f203d395bdc21346d4") } > db.demo195.insertOne({"Subject":"MongoDB"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3af3f703d395bdc21346d5") } > db.demo195.insertOne({"Subject":"Java"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3af3fa03d395bdc21346d6") }Display all documents from a collection with the help of find() method −> db.demo195.find();This will produce the following output −{ "_id" : ObjectId("5e3af3f203d395bdc21346d4"), "Subject" : "MySQL" } { "_id" : ObjectId("5e3af3f703d395bdc21346d5"), "Subject" : "MongoDB" } { "_id" : ObjectId("5e3af3fa03d395bdc21346d6"), "Subject" : "Java" }Following is the query to return a ... Read More