To get the sum, use $sum along with aggregate(). Let us create a collection with documents −
> db.demo337.insertOne({"Amount":100}); { "acknowledged" : true, "insertedId" : ObjectId("5e5231e5f8647eb59e56209b") } > db.demo337.insertOne({"Amount":500}); { "acknowledged" : true, "insertedId" : ObjectId("5e5231e9f8647eb59e56209c") } > db.demo337.insertOne({"Amount":400}); { "acknowledged" : true, "insertedId" : ObjectId("5e5231ebf8647eb59e56209d") }
Display all documents from a collection with the help of find() method −
> db.demo337.find();
This will produce the following output −
{ "_id" : ObjectId("5e5231e5f8647eb59e56209b"), "Amount" : 100 } { "_id" : ObjectId("5e5231e9f8647eb59e56209c"), "Amount" : 500 } { "_id" : ObjectId("5e5231ebf8647eb59e56209d"), "Amount" : 400 }
Following is the query to calculate sum in MongoDB −
> db.demo337.aggregate( ... [ ... { ... $group: ... { ... _id:null, ... totalAmount: { $sum:"$Amount" } ... } ... } ... ] ... );
This will produce the following output −
{ "_id" : null, "totalAmount" : 1000 }