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Database Articles
Page 404 of 546
Reverse array field in MongoDB?
To reverse array field in MongoDB, you can use forEach(). Let us first create a collection with documents −> db.reverseArrayDemo.insertOne({"Skills":["C", "Java"]}); { "acknowledged" : true, "insertedId" : ObjectId("5ccddf99dceb9a92e6aa1946") }Following is the query to display all documents from a collection with the help of find() method −> db.reverseArrayDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5ccddf99dceb9a92e6aa1946"), "Skills" : [ "C", "Java" ] }Here is the query to reverse array field in MongoDB −> db.reverseArrayDemo.find().forEach(function (myDocument) { ... var arrayValue = [ myDocument.Skills[1], myDocument.Skills[0] ]; ... db.reverseArrayDemo.update(myDocument, { ...
Read MoreIterate a cursor and print a document in MongoDB?
For this, use printjson. Let us first create a collection with documents −> db.cursorDemo.insertOne({"StudentFullName":"John Smith", "StudentAge":23}); { "acknowledged" : true, "insertedId" : ObjectId("5cc7f0d08f9e6ff3eb0ce442") } > db.cursorDemo.insertOne({"StudentFullName":"John Doe", "StudentAge":21}); { "acknowledged" : true, "insertedId" : ObjectId("5cc7f0df8f9e6ff3eb0ce443") } > db.cursorDemo.insertOne({"StudentFullName":"Carol Taylor", "StudentAge":20}); { "acknowledged" : true, "insertedId" : ObjectId("5cc7f0eb8f9e6ff3eb0ce444") } > db.cursorDemo.insertOne({"StudentFullName":"Chris Brown", "StudentAge":24}); { "acknowledged" : true, "insertedId" : ObjectId("5cc7f0f88f9e6ff3eb0ce445") }Following is the query to display all documents from a collection with the help of find() method −> db.cursorDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cc7f0d08f9e6ff3eb0ce442"), "StudentFullName" : "John ...
Read MoreHow to find datatype of all the fields in MongoDB?
Use typeof to find datatype of all the fields −typeof db.yourCollectionName.findOne().yourFieldName;Let us first create a collection with documents −> db.findDataTypeDemo.insertOne({"ClientName":"Chris", "isMarried":false}); { "acknowledged" : true, "insertedId" : ObjectId("5ccf2064dceb9a92e6aa1952") }Following is the query to display all documents from a collection with the help of find() method −> db.findDataTypeDemo.findOne();This will produce the following output −{ "_id" : ObjectId("5ccf2064dceb9a92e6aa1952"), "ClientName" : "Chris", "isMarried" : false }Following is the query to find datatype of a field in MongoDB −> typeof db.findDataTypeDemo.findOne().isMarried;This will produce the following output −BooleanHere is the query to get the data type of another field −> ...
Read MoreRemove and update the existing record in MongoDB?
You can use only $pull operator that removes and updates the existing record in MongoDB. Let us first create a collection with documents −> db.removeDemo.insertOne( ... { ... "UserName" : "Larry", ... "UserDetails" : [ ... { ... "_id" : 101, ... "UserEmailId" : "976Larry@gmail.com", ... } ... ] ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5cc7f9f88f9e6ff3eb0ce446") } > db.removeDemo.insertOne( ... { ... ...
Read MoreHow to perform intersection of sets between the documents in a single collection in MongoDB?
You can use $setIntersection for this. Let us first create a collection with documents −> db.setInterSectionDemo.insertOne( ... {"_id":101, "Value1":[55, 67, 89]} ... ); { "acknowledged" : true, "insertedId" : 101 } > db.setInterSectionDemo.insertOne( ... {"_id":102, "Value2":[90, 45, 55]} ... ); { "acknowledged" : true, "insertedId" : 102 } > db.setInterSectionDemo.insertOne( ... {"_id":103, "Value3":[92, 67, 45]} ... ); { "acknowledged" : true, "insertedId" : 103 }Following is the query to display all documents from a collection with the help of find() method −> db.setInterSectionDemo.find().pretty();This will produce the following output −{ "_id" : 101, "Value1" : [ 55, 67, ...
Read MoreWhat is the syntax for boolean values in MongoDB?
You can use $eq as well as $ne operator for boolean values. Let us first create a collection with documents −> db.booleanQueryDemo.insertOne({"UserName":"John", "UserAge":23, "isMarried":true}); { "acknowledged" : true, "insertedId" : ObjectId("5cc815c08f9e6ff3eb0ce44a") } > db.booleanQueryDemo.insertOne({"UserName":"Chris", "UserAge":21, "isMarried":false}); { "acknowledged" : true, "insertedId" : ObjectId("5cc815d08f9e6ff3eb0ce44b") } > db.booleanQueryDemo.insertOne({"UserName":"Robert", "UserAge":24, "isMarried":false}); { "acknowledged" : true, "insertedId" : ObjectId("5cc815dc8f9e6ff3eb0ce44c") } > db.booleanQueryDemo.insertOne({"UserName":"David", "UserAge":26, "isMarried":true}); { "acknowledged" : true, "insertedId" : ObjectId("5cc815ed8f9e6ff3eb0ce44d") }Following is the query to display all documents from a collection with the help of find() method −> db.booleanQueryDemo.find().pretty();This will produce the following output −{ ...
Read MoreHow to prepend string to entire column in MongoDB?
Prepend string to entire column in MongoDB using aggregate framework. Let us first create a collection with documents −> db.prependDemo.insertOne({"StudentFirstName":"John"}); { "acknowledged" : true, "insertedId" : ObjectId("5ccf3bcedceb9a92e6aa1955") } > db.prependDemo.insertOne({"StudentFirstName":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5ccf3bd3dceb9a92e6aa1956") } > db.prependDemo.insertOne({"StudentFirstName":"Robert"}); { "acknowledged" : true, "insertedId" : ObjectId("5ccf3bd8dceb9a92e6aa1957") }Following is the query to display all documents from a collection with the help of find() method −> db.prependDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5ccf3bcedceb9a92e6aa1955"), "StudentFirstName" : "John" } { "_id" : ObjectId("5ccf3bd3dceb9a92e6aa1956"), "StudentFirstName" : "Chris" } { "_id" : ObjectId("5ccf3bd8dceb9a92e6aa1957"), ...
Read MoreUpdate object at specific Array Index in MongoDB?
To update object at specific array index, use update() in MongoDB. Let us first create a collection with documents −> db.updateObjectDemo.insertOne( ... { ... id : 101, ... "StudentDetails": ... [ ... [ ... { ... "StudentName": "John" ... }, ... { "StudentName": "Chris" } ... ], ... [ { "StudentName": "Carol" }, ...
Read MoreIs it possible to achieve a slice chain in MongoDB?
Yes, you can achieve this using aggregate framework. Let us first create a collection with documents −> db.sliceOfSliceDemo.insertOne( ... { ... "Name": "John", ... "Details": [["First 1:1", "First 1:2"], ["second 2:1", "Second 2:2"]] ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5ccf3fcfdceb9a92e6aa195a") }Following is the query to display all documents from a collection with the help of find() method −> db.sliceOfSliceDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5ccf3fcfdceb9a92e6aa195a"), "Name" : "John", "Details" : [ [ "First ...
Read MoreHow to pull all elements from an array in MongoDB without any condition?
You can use $set operator for this. Let us first create a collection with documents −> db.pullAllElementDemo.insertOne( ... { ... "StudentId":101, ... "StudentDetails" : [ ... { ... ... "StudentName": "Carol", ... "StudentAge":21, ... "StudentCountryName":"US" ... }, ... { ... "StudentName": "Chris", ... "StudentAge":24, ... ...
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