Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
Big Data Analytics Articles
Page 108 of 135
MongoDB query for Partial Object in an array
Let us first create a collection with documents −> db.queryForPartialObjectDemo.insertOne({_id:new ObjectId(), "StudentDetails": [{"StudentId":1, "StudentName":"Chris"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5cdfcf55bf3115999ed51206") } > db.queryForPartialObjectDemo.insertOne({_id:new ObjectId(), "StudentDetails": [{"StudentId":2, "StudentName":"David"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5cdfcf55bf3115999ed51207") }Following is the query to display all documents from a collection with the help of find() method −> db.queryForPartialObjectDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cdfcf55bf3115999ed51206"), "StudentDetails" : [ { "StudentId" : 1, "StudentName" : "Chris" } ] } { "_id" ...
Read MoreFind the exact match in array without using the $elemMatch operator in MongoDB?
As an alternative, use the $eq operator. Let us first create a collection with documents −> db.equalDemo.insertOne({_id:1, "StudentFriendNames":["John", "Carol", "Sam"]}); { "acknowledged" : true, "insertedId" : 1 } > db.equalDemo.insertOne({_id:2, "StudentFriendNames":null}); { "acknowledged" : true, "insertedId" : 2 } > db.equalDemo.insertOne({_id:3, "StudentFriendNames":["Carol"]}); { "acknowledged" : true, "insertedId" : 3 } > db.equalDemo.insertOne({_id:4, "StudentFriendNames":["Sam"]}); { "acknowledged" : true, "insertedId" : 4 }Following is the query to display all documents from a collection with the help of find() method −> db.equalDemo.find();This will produce the following output −{ "_id" : 1, "StudentFriendNames" : [ "John", "Carol", "Sam" ] } { "_id" : 2, ...
Read MoreHow to use $regex in MongoDB?
Following is the syntax to use $regex in MongoDB −db.yourCollectionName.find({yourFieldName: { $regex: yourValue}});Let us first create a collection with documents −> db.regularExpressionDemo.insertOne({"UserName":"John"}); { "acknowledged" : true, "insertedId" : ObjectId("5cdffc25bf3115999ed51210") } > db.regularExpressionDemo.insertOne({"UserName":"JOHN"}); { "acknowledged" : true, "insertedId" : ObjectId("5cdffc2ebf3115999ed51211") } > db.regularExpressionDemo.insertOne({"UserName":"john"}); { "acknowledged" : true, "insertedId" : ObjectId("5cdffc35bf3115999ed51212") } > db.regularExpressionDemo.insertOne({"UserName":"JoHn"}); { "acknowledged" : true, "insertedId" : ObjectId("5cdffc3ebf3115999ed51213") }Following is the query to display all documents from a collection with the help of find() method −> db.regularExpressionDemo.find();This will produce the following output −{ "_id" : ObjectId("5cdffc25bf3115999ed51210"), "UserName" : "John" } { ...
Read MoreHow to add an extra field in a sub document in MongoDB?
You can use update(). Let us first create a collection with documents −> db.addExtraFieldDemo.insertOne( { "_id": 1, "UserName": "Larry" , "UserOtherDetails":[ { "UserCountryName": "US", "UserAge":23 }, { "UserCountryName": "UK", "UserAge":24 } ] } ); { "acknowledged" : true, "insertedId" : 1 }Following is the query to ...
Read MoreHow to get the matching document inside an array in MongoDB?
To get the matching document, use $elemMatch. Let us first create a collection with documents −> db.getMatchingDocumentDemo.insertOne( { _id :1, "UserDetails":[ { "UserName":"John", "UserAge":23 } ] } ); { "acknowledged" : true, "insertedId" : 1 } > db.getMatchingDocumentDemo.insertOne( { _id :2, "UserDetails":[ { "UserName":"Larry", "UserAge":24 } ] } ); { "acknowledged" : true, "insertedId" : 2 }Following is the query to display all documents from a collection with the ...
Read MoreMongoDB query to return specific fields from an array?
To return specific fields, use aggregate $project. Let us first create a collection with documents −> db.returnSpecificFieldDemo.insertOne( { "StudentId":1, "StudentDetails": [ { "StudentName":"Larry", "StudentAge":21, "StudentCountryName":"US" }, { "StudentName":"Chris", "StudentAge":23, "StudentCountryName":"AUS" } ] } ); { "acknowledged" ...
Read MoreMongoDB query to replace value with aggregation?
Use aggregate framework along with $literal operator. Let us first create a collection with documents −> db.replaceValueDemo.insertOne( { _id : 100, "EmployeeName" :"Chris", "EmployeeOtherDetails": { "EmployeeDesignation" : "HR", "EmployeeAge":27 } } ); { "acknowledged" : true, "insertedId" : 100 } > db.replaceValueDemo.insertOne( { _id : 101, "EmployeeName" :"David", "EmployeeOtherDetails": { "EmployeeDesignation" : "Tester", "EmployeeAge":26 } } ...
Read MoreHow to search for string or number in a field with MongoDB?
You can use $in operator for this. Let us first create a collection with documents −> db.searchForStringOrNumberDemo.insertOne( { "_id": new ObjectId(), "StudentName": "Larry", "StudentDetails": { "StudentMarks": { "StudentMongoDBMarks": [44] } } } ); { "acknowledged" : true, "insertedId" : ObjectId("5ce2407c36e8b255a5eee944") } > db.searchForStringOrNumberDemo.insertOne( { "_id": new ObjectId(), "StudentName": "Larry", "StudentDetails": { "StudentMarks": { "StudentMongoDBMarks": ["44"] } } } ); { "acknowledged" : true, "insertedId" : ObjectId("5ce240f036e8b255a5eee945") }Following is ...
Read MoreWhat is to be done when MongoDB takes too much time to find the record?
To reduce the time to find record in MongoDB, you can use index. Following is the syntax −db.yourCollectionName.createIndex({yourFieldName:1});You can follow the below approaches to create index for field names based on number, text, hash, etc.First ApproachLet us create an index. Following is the query −> db.takeLessTimeToSearchDemo.createIndex({"EmployeeName":1}); { "createdCollectionAutomatically" : true, "numIndexesBefore" : 1, "numIndexesAfter" : 2, "ok" : 1 }Second ApproachTo understand the above concept, let us create another index −> db.takeLessTimeToSearchDemo1.createIndex({"EmployeeName":"text"}); { "createdCollectionAutomatically" : true, "numIndexesBefore" : 1, "numIndexesAfter" : 2, "ok" : 1 }Third ApproachLet us now create another index −> db.takeLessTimeToSearchDemo2.createIndex({"EmployeeName":"hashed"}); { "createdCollectionAutomatically" : true, "numIndexesBefore" : 1, "numIndexesAfter" : 2, "ok" : 1 }
Read MoreHow to update _id field in MongoDB?
You can’t directly update _id field i.e. write some script to update. Let us first create a collection with documents −> db.updatingIdFieldDemo.insertOne({"StudentName":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5ce271bb36e8b255a5eee949") }Following is the query to display all documents from a collection with the help of find() method −> db.updatingIdFieldDemo.find();This will produce the following output −{ "_id" : ObjectId("5ce271bb36e8b255a5eee949"), "StudentName" : "Chris" }Following is the query to update _id field in MongoDB −> var myDocument=db.updatingIdFieldDemo.findOne({StudentName:"Chris"}); > myDocument._id = 101; 101 > db.updatingIdFieldDemo.save(myDocument); WriteResult({ "nMatched" : 0, "nUpserted" : 1, "nModified" : 0, "_id" : 101 }) > db.updatingIdFieldDemo.remove({_id:ObjectId("5ce271bb36e8b255a5eee949")}); WriteResult({ ...
Read More