Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
How to remove all documents from a collection except a single document in MongoDB?
To remove all documents from a collection except a single document in MongoDB, use remove() based on some condition. Let us create a collection with documents. Following is the query
>db.removeAllDocumentsExceptOneDemo.insertOne({"StudentName":"Larry","StudentAge":21});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9c9de42d66697741252478")
}
>db.removeAllDocumentsExceptOneDemo.insertOne({"StudentName":"Mike","StudentAge":21,"StudentCountryName":"US"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9c9dea2d66697741252479")
}
>db.removeAllDocumentsExceptOneDemo.insertOne({"StudentName":"Chris","StudentAge":24,"StudentCountryName":"AUS"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9c9def2d6669774125247a")
}Following is the query to display all documents from a collection with the help of find() method
> db.removeAllDocumentsExceptOneDemo.find().pretty();
This will produce the following output
{
"_id" : ObjectId("5c9c9de42d66697741252478"),
"StudentName" : "Larry",
"StudentAge" : 21
}
{
"_id" : ObjectId("5c9c9dea2d66697741252479"),
"StudentName" : "Mike",
"StudentAge" : 21,
"StudentCountryName" : "US"
}
{
"_id" : ObjectId("5c9c9def2d6669774125247a"),
"StudentName" : "Chris",
"StudentAge" : 24,
"StudentCountryName" : "AUS"
}Following is the query to remove all documents from a collection except a single document i.e. with StudentAge 24
> db.removeAllDocumentsExceptOneDemo.remove({ StudentAge: { $ne: 24 } } );
WriteResult({ "nRemoved" : 2 })Let us check all the documents now. Following is the query
> db.removeAllDocumentsExceptOneDemo.find().pretty();
Following is the output displaying only a single document
{
"_id" : ObjectId("5c9c9def2d6669774125247a"),
"StudentName" : "Chris",
"StudentAge" : 24,
"StudentCountryName" : "AUS"
}
Updated on: 30-Jul-2019
604 Views
Advertisements