- 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
Match between fields in MongoDB aggregation framework?
You can use $cmp operator for this. To understand the concept, let us create a collection with the document. The query to create a collection with a document is as follows −
> db.matchBetweenFieldsDemo.insertOne({"FirstValue":40,"SecondValue":70}); { "acknowledged" : true, "insertedId" : ObjectId("5c92c9625259fcd19549980d") } > db.matchBetweenFieldsDemo.insertOne({"FirstValue":20,"SecondValue":5}); { "acknowledged" : true, "insertedId" : ObjectId("5c92c96b5259fcd19549980e") }
Display all documents from a collection with the help of find() method. The query is as follows −
> db.matchBetweenFieldsDemo.find().pretty();
The following is the output −
{ "_id" : ObjectId("5c92c9625259fcd19549980d"), "FirstValue" : 40, "SecondValue" : 70 } { "_id" : ObjectId("5c92c96b5259fcd19549980e"), "FirstValue" : 20, "SecondValue" : 5 }
Here is the query to $match between fields in aggregation framework −
> db.matchBetweenFieldsDemo.aggregate([ ... {$project: { ... ... firstGreaterThanOrNot: {$cmp: ['$FirstValue', '$SecondValue']} ... }}, ... {$match: {firstGreaterThanOrNot:{$gt: 0}}} ... ]);
The following is the output −
{ "_id" : ObjectId("5c92c96b5259fcd19549980e"), "firstGreaterThanOrNot" : 1 }
Advertisements