Mongodb group by queries Lets say one of my items in a collection looks like that:

{
  User:123
  Grade : 100
}

I want to sum up the grades for each student so i have this output:

123: 100, 445: 30 etc

Im normal sql, its the equivalent of a group by + sum() query. How can i do it with mongo?
You will have to use the mongodb aggregation framework.

Check this example: https://docs.mongodb.org/manual/tutorial/aggregation-zip-code-data-set/