Template
single collection
multiple collections
mgodatagen
update
indexe
explain
Stage
Database
bson
mgodatagen
[{a:5,b:3},{a:2,b:1},]
Query
db.collection.aggregate([{$project:{_id:0,c:{"$add":["$a","$b"]},d:{"$multiply":["$a","$c"]}}}])
Result