For this, you can use aggregate(). Let us create a collection with documents −
> db.demo142.insertOne({"Value":50}); { "acknowledged" : true, "insertedId" : ObjectId("5e32e9c6fdf09dd6d08539b2") } > db.demo142.insertOne({"Value":45}); { "acknowledged" : true, "insertedId" : ObjectId("5e32e9cafdf09dd6d08539b3") } > db.demo142.insertOne({"Value":60}); { "acknowledged" : true, "insertedId" : ObjectId("5e32e9cdfdf09dd6d08539b4") } > db.demo142.insertOne({"Value":55}); { "acknowledged" : true, "insertedId" : ObjectId("5e32e9d0fdf09dd6d08539b5") } > db.demo142.insertOne({"Value":50}); { "acknowledged" : true, "insertedId" : ObjectId("5e32e9d9fdf09dd6d08539b6") }
Display all documents from a collection with the help of find() method −
> db.demo142.find();
This will produce the following output −
{ "_id" : ObjectId("5e32e9c6fdf09dd6d08539b2"), "Value" : 50 } { "_id" : ObjectId("5e32e9cafdf09dd6d08539b3"), "Value" : 45 } { "_id" : ObjectId("5e32e9cdfdf09dd6d08539b4"), "Value" : 60 } { "_id" : ObjectId("5e32e9d0fdf09dd6d08539b5"), "Value" : 55 } { "_id" : ObjectId("5e32e9d9fdf09dd6d08539b6"), "Value" : 50 }
Following is the query to push query results into variable −
> var query = db.demo142.aggregate( ... { "$group": { "_id": null, "MaxValue": { "$max": "$Value" } } } ... ]); > var largestValue= query.toArray()[0]["MaxValue"]; > printjson(largestValue);
This will produce the following output −
60