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MongoDB Articles
Page 81 of 111
Check if a list is not empty in MongoDB?
For this, use the $size operator. Let us first create a collection with documents −> db.checkIfListIsNotEmptyDemo.insertOne({"UserFriendGroup":["John", "David"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cdd99e8bf3115999ed511f7") } > db.checkIfListIsNotEmptyDemo.insertOne({"UserFriendGroup":["Carol"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cdd99e9bf3115999ed511f8") } > db.checkIfListIsNotEmptyDemo.insertOne({"UserFriendGroup":[]}); { "acknowledged" : true, "insertedId" : ObjectId("5cdd99ebbf3115999ed511f9") } > db.checkIfListIsNotEmptyDemo.insertOne({"UserFriendGroup":[null]}); { "acknowledged" : true, "insertedId" : ObjectId("5cdd99f2bf3115999ed511fa") } > db.checkIfListIsNotEmptyDemo.insertOne({"UserFriendGroup":[]}); { "acknowledged" : true, "insertedId" : ObjectId("5cdd99f6bf3115999ed511fb") }Following is the query to display all documents from a collection with the help of find() method −> db.checkIfListIsNotEmptyDemo.find().pretty();This will produce the following output −{ ...
Read MoreFind data for specific date in MongoDB?
Let’s say you have saved the Login date of users. Now, you want the count of records for specific date only i.e. login date. For this, use $gte and $lt operator along with count(). Let us first create a collection with documents −> db.findDataByDateDemo.insertOne({"UserName":"John", "UserLoginDate":new ISODate("2019-01-31")}); { "acknowledged" : true, "insertedId" : ObjectId("5cdd8cd7bf3115999ed511ed") } > db.findDataByDateDemo.insertOne({"UserName":"Larry", "UserLoginDate":new ISODate("2019-02-01")}); { "acknowledged" : true, "insertedId" : ObjectId("5cdd8ce7bf3115999ed511ee") } > db.findDataByDateDemo.insertOne({"UserName":"Sam", "UserLoginDate":new ISODate("2019-05-02")}); { "acknowledged" : true, "insertedId" : ObjectId("5cdd8cf3bf3115999ed511ef") } > db.findDataByDateDemo.insertOne({"UserName":"David", "UserLoginDate":new ISODate("2019-05-16")}); { "acknowledged" : true, "insertedId" : ObjectId("5cdd8d00bf3115999ed511f0") } > db.findDataByDateDemo.insertOne({"UserName":"Carol", ...
Read MoreMongoDB Limit fields and slice projection together?
Use the $slice operator. Let us first create a collection with documents −> db.limitAndSliceProjectionDemo.insertOne( { "_id" : 101, "UserName" : "Carol", "UserAge" : 26, "UserMesssage" : [ "Hi", "Hello", "Bye", "Awesome", "Good", "Bad", "Nice", "Good Night", "Good Morning" ] } ); { "acknowledged" : true, "insertedId" : ...
Read MoreHow to add a sub-document to sub-document array in MongoDB?
Use the $push operator to add a sub-document. Let us first create a collection with documents −> db.subDocumentToSubDocumentDemo.insertOne( { "_id" :101, "StudentName" : "Larry", "StudentAge" : 21, "StudentDetails" : [ { "StudentCountryName" : "US", "StudentFavouriteSubjectList" : [ ] } ] } ); { "acknowledged" : true, "insertedId" : 101 }Following is the query to display all documents from a collection with the help ...
Read MoreMongoDB query to find a value from JSON like data?
To fund a value from JSON data, use the find() along with dot(.) notation. Let us first create a collection with documents −> db.findValueFromJsonDemo.insertOne( { "UserDetails": [{ "_id": new ObjectId(), "UserName": "Carol", "UserMessage": "Hi" }], "UserFriendsName": ["John", "Sam"] } ); { "acknowledged" : true, "insertedId" : ObjectId("5cdf8a4cbf3115999ed511fd") }Following is the query to display all documents from a collection with the help of find() method −> db.findValueFromJsonDemo.find().pretty();This will produce the following output −{ "_id" : ...
Read MoreWrite an equality in MongoDB without using $eq operator
Let us first create a collection with documents -> db.operatorDemo.insertOne({"StudentSubject":["MongoDB", "MySQL", "Java"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cef94eaef71edecf6a1f6a2") } > db.operatorDemo.insertOne({"StudentSubject":["Java", "C", "C++"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cef94faef71edecf6a1f6a3") }Display all documents from a collection with the help of find() method -> db.operatorDemo.find().pretty();Output{ "_id" : ObjectId("5cef94eaef71edecf6a1f6a2"), "StudentSubject" : [ "MongoDB", "MySQL", "Java" ] } { "_id" : ObjectId("5cef94faef71edecf6a1f6a3"), "StudentSubject" : [ "Java", "C", "C++" ] }Following is the query for ...
Read MoreRemoving an array element from MongoDB collection using update() and $pull
Let us first create a collection with documents -> db.removingAnArrayElementDemo.insertOne({"UserMessage":["Hi", "Hello", "Bye"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cef97bdef71edecf6a1f6a4") }Display all documents from a collection with the help of find() method -> db.removingAnArrayElementDemo.find().pretty();Output{ "_id" : ObjectId("5cef97bdef71edecf6a1f6a4"), "UserMessage" : [ "Hi", "Hello", "Bye" ] }Following is the query to remove an array element from MongoDB -> db.removingAnArrayElementDemo.update( {_id:ObjectId("5cef97bdef71edecf6a1f6a4")}, { "$pull": { "UserMessage": "Hello" } } ); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })Let us check the document once again:> db.removingAnArrayElementDemo.find().pretty();Output{ ...
Read MoreProjection result as an array of selected items in MongoDB?
Use the distinct() for this, since it finds the distinct values for a specified field across a single collection or view and returns the results in an array.Let us first create a collection with documents −> db.projectionListDemo.insertOne({"_id":"1", "Subject":["MongoDB", "MySQL", "Java"]}); { "acknowledged" : true, "insertedId" : "1" } > db.projectionListDemo.insertOne({"_id":"2", "Subject":["MongoDB", "C", "C++"]}); { "acknowledged" : true, "insertedId" : "2" } > db.projectionListDemo.insertOne({"_id":"3", "Subject":["Java", "Python"]}); { "acknowledged" : true, "insertedId" : "3" }Display all documents from a collection with the help of find() method −> db.projectionListDemo.find().pretty();Output{ "_id" : "1", "Subject" : [ "MongoDB", "MySQL", "Java" ] } { "_id" : ...
Read MoreMongoDB query to find data from an array inside an object?
Let us first create a collection with documents −> db.findDataDemo.insertOne( { "_id": new ObjectId(), "CustomerName":"John", "CustomerDetails" : { "CountryName" : [ "AUS" ], "isMarried" : [ false ] } } ); { "acknowledged" : true, "insertedId" : ObjectId("5cefa5eeef71edecf6a1f6a5") } > db.findDataDemo.insertOne( { "_id": new ObjectId(), "CustomerName":"Carol", ...
Read MoreMongoDB query to get last inserted document?
To get last inserted document, use sort() along with limit(1).Let us first create a collection with documents −> db.getLastInsertedDocument.insertOne({"Name":"John"}); { "acknowledged" : true, "insertedId" : ObjectId("5cefb17eef71edecf6a1f6a8") } > db.getLastInsertedDocument.insertOne({"Name":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5cefb181ef71edecf6a1f6a9") } > db.getLastInsertedDocument.insertOne({"Name":"Robert"}); { "acknowledged" : true, "insertedId" : ObjectId("5cefb185ef71edecf6a1f6aa") }Display all documents from a collection with the help of find() method −> db.getLastInsertedDocument.find();Output{ "_id" : ObjectId("5cefb17eef71edecf6a1f6a8"), "Name" : "John" } { "_id" : ObjectId("5cefb181ef71edecf6a1f6a9"), "Name" : "Chris" } { "_id" : ObjectId("5cefb185ef71edecf6a1f6aa"), "Name" : "Robert" }Following is the query to get last inserted document −> db.getLastInsertedDocument.find({}).sort({_id:-1}).limit(1);Output{ "_id" ...
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