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Found 1349 Articles for MongoDB
![Nishtha Thakur](https://www.tutorialspoint.com/assets/profiles/13598/profile/60_104893-1512719058.jpg)
222 Views
Use aggregate framework along with $ifNull operator for this. The $concatArrays in aggregation is used to concatenate arrays. Let us first create a collection with documents −>db.concatenateArraysDemo.insertOne({"FirstSemesterSubjects": ["MongoDB", "MySQL", "Java"], "SecondSemesterSubjects":["C", "C++", ]}); { "acknowledged" : true, "insertedId" : ObjectId("5cd687707924bb85b3f4895c") } > db.concatenateArraysDemo.insertOne({"FirstSemesterSubjects":["C#", "Ruby", "Python"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cd687927924bb85b3f4895d") } >db.concatenateArraysDemo.insertOne({"FirstSemesterSubjects":["HTML", "CSS", "Javascript"], "SecondSemesterSubjects":["CSS", "Javascript"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cd687bb7924bb85b3f4895e") }Following is the query to display all documents from a collection with the help of find() method −> db.concatenateArraysDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cd687707924bb85b3f4895c"), ... Read More
![Smita Kapse](https://www.tutorialspoint.com/assets/profiles/13597/profile/60_103706-1512718957.jpg)
2K+ Views
You can use $in operator to check if a value is in an array or not. Let us first create a collection with documents −> db.valueInArrayDemo.insertOne({"UserName":"John", "UserMessage":["Hi", "Hello", "Bye"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cd684cf7924bb85b3f48959") } > db.valueInArrayDemo.insertOne({"UserName":"Larry", "UserMessage":["Thank You", "Amazing", "Nice"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cd684d27924bb85b3f4895a") } >db.valueInArrayDemo.insertOne({"UserName":"Carol", "UserMessage":["Awesome", "Bye", "Cool"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cd684d87924bb85b3f4895b") }Following is the query to display all documents from a collection with the help of find() method −> db.valueInArrayDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cd684cf7924bb85b3f48959"), "UserName" : "John", "UserMessage" : [ "Hi", "Hello", ... Read More
![Anvi Jain](https://www.tutorialspoint.com/assets/profiles/13591/profile/60_98631-1512716973.jpg)
289 Views
To push elements to an existing array, use $addToSet operator along with update(). Let us first create a collection with documents −> db.pushElements.insertOne({"Comments":["Good", "Awesome", "Nice"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cd682597924bb85b3f48953") }Following is the query to display all documents from a collection with the help of find() method −> db.pushElements.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cd682597924bb85b3f48953"), "Comments" : [ "Good", "Awesome", "Nice" ] }Following is the query to push elements to an existing array in MongoDB −> db.pushElements.update( {_id:ObjectId("5cd682597924bb85b3f48953")}, { ... Read More
![Nishtha Thakur](https://www.tutorialspoint.com/assets/profiles/13598/profile/60_104893-1512719058.jpg)
1K+ Views
For this, work with the concept of forEach(). Let us first create a collection with documents −> db.printDocuementValueDemo.insertOne({"InstructorName":"John Smith"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd6804f7924bb85b3f48950") } > db.printDocuementValueDemo.insertOne({"InstructorName":"Sam Williams"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd680577924bb85b3f48951") } > db.printDocuementValueDemo.insertOne({"InstructorName":"David Miller"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd680637924bb85b3f48952") }Following is the query to display all documents from a collection with the help of find() method −> db.printDocuementValueDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cd6804f7924bb85b3f48950"), "InstructorName" : "John Smith" } { "_id" : ObjectId("5cd680577924bb85b3f48951"), "InstructorName" : "Sam Williams" } ... Read More
![Smita Kapse](https://www.tutorialspoint.com/assets/profiles/13597/profile/60_103706-1512718957.jpg)
429 Views
For this, you need to write some code using forEach(). Let us first create a collection with documents −> db.removingWhiteSpaceDemo.insertOne({"Title":" Introduction to java "}); { "acknowledged" : true, "insertedId" : ObjectId("5cd66f387924bb85b3f4894c") }Following is the query to display all documents from a collection with the help of find() method −> db.removingWhiteSpaceDemo.find();This will produce the following output −{ "_id" : ObjectId("5cd66f387924bb85b3f4894c"), "Title" : " Introduction to java " }Following is the query to remove white spaces (leading and trailing) from string value −> db.removingWhiteSpaceDemo.find({}, {"Title": 1 }).forEach(function(myDocument) { myDocument.Title = myDocument.Title.trim(); db.removingWhiteSpaceDemo.update( { "_id": myDocument._id ... Read More
![Anvi Jain](https://www.tutorialspoint.com/assets/profiles/13591/profile/60_98631-1512716973.jpg)
466 Views
You can use $literal operator along with aggregate framework. Let us first create a collection with documents −> db.fieldWithStaticValue.insertOne({"Name":"Larry", "Age":24}); { "acknowledged" : true, "insertedId" : ObjectId("5cd6554c7924bb85b3f48948") } > db.fieldWithStaticValue.insertOne({"Name":"Chris", "Age":23}); { "acknowledged" : true, "insertedId" : ObjectId("5cd655567924bb85b3f48949") } > db.fieldWithStaticValue.insertOne({"Name":"David", "Age":26}); { "acknowledged" : true, "insertedId" : ObjectId("5cd655607924bb85b3f4894a") }Following is the query to display all documents from a collection with the help of find() method −> db.fieldWithStaticValue.find();This will produce the following output −{ "_id" : ObjectId("5cd6554c7924bb85b3f48948"), "Name" : "Larry", "Age" : 24 } { "_id" : ObjectId("5cd655567924bb85b3f48949"), "Name" : "Chris", "Age" : 23 ... Read More
![Nishtha Thakur](https://www.tutorialspoint.com/assets/profiles/13598/profile/60_104893-1512719058.jpg)
107 Views
You can use $in operator. Let us first create a collection with documents −> db.tagCountDemo.insertOne({"ListOfNames":["John", "Sam", "Carol"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cd64b387924bb85b3f48944") } > db.tagCountDemo.insertOne({"ListOfNames":["Bob", "David", "John"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cd64b4b7924bb85b3f48945") } > db.tagCountDemo.insertOne({"ListOfNames":["Mike", "Robert", "Chris"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cd64b5d7924bb85b3f48946") } > db.tagCountDemo.insertOne({"ListOfNames":["James", "Carol", "Jace"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cd64b717924bb85b3f48947") }Following is the query to display all documents from a collection with the help of find() method −> db.tagCountDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cd64b387924bb85b3f48944"), "ListOfNames" : ... Read More
![Smita Kapse](https://www.tutorialspoint.com/assets/profiles/13597/profile/60_103706-1512718957.jpg)
251 Views
To sort by sub-document match, you can use aggregate framework. Let us first create a collection with documents −> db.sortBySubDocumentsDemo.insertOne( { "StudentName": "Chris", "StudentDetails": [ { "Age":21, "StudentScore":91 }, { "Age":22, "StudentScore":99 }, { "Age":21, "StudentScore":93 ... Read More
![Smita Kapse](https://www.tutorialspoint.com/assets/profiles/13597/profile/60_103706-1512718957.jpg)
265 Views
You can use $lte operator along with Date() for this. Let us first create a collection with documents. Here, we have set the date 2019-05-11, which is the current date −> db.getDocumentsExpiredDemo.insertOne({"ArrivalDate":new ISODate("2019-05-11")}); { "acknowledged" : true, "insertedId" : ObjectId("5cd563b17924bb85b3f4893b") } > db.getDocumentsExpiredDemo.insertOne({"ArrivalDate":new ISODate("2019-01-01")}); { "acknowledged" : true, "insertedId" : ObjectId("5cd563bf7924bb85b3f4893c") } > db.getDocumentsExpiredDemo.insertOne({"ArrivalDate":new ISODate("2019-05-10")}); { "acknowledged" : true, "insertedId" : ObjectId("5cd563ca7924bb85b3f4893d") } > db.getDocumentsExpiredDemo.insertOne({"ArrivalDate":new ISODate("2019-02-01")}); { "acknowledged" : true, "insertedId" : ObjectId("5cd563e77924bb85b3f4893e") }Following is the query to display all documents from a collection with the help of find() method −> db.getDocumentsExpiredDemo.find().pretty();This ... Read More
![Anvi Jain](https://www.tutorialspoint.com/assets/profiles/13591/profile/60_98631-1512716973.jpg)
293 Views
To update array in MongoDB document by variable index, use the below syntax. Here, yourIndexValue in the index value, where yourIndexVariableName is the variable name for index −var yourIndexVariableName= yourIndexValue, anyVariableName= { "$set": {} }; yourVariableName["$set"]["yourFieldName."+yourIndexVariableName] = "yourValue"; db.yourCollectionName.update({ "_id": yourObjectId}, yourVariableName);Let us first create a collection with documents −> db.updateByVariableDemo.insertOne({"StudentSubjects":["MySQL", "Java", "SQL Server", "PL/SQL"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cd553c37924bb85b3f4893a") }Following is the query to display all documents from a collection with the help of find() method −> db.updateByVariableDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cd553c37924bb85b3f4893a"), "StudentSubjects" : [ ... Read More