可以的

在MongoDB中

db.coll.group(
           {key: { a:true, b:true },
            cond: { active:1 },
            reduce: function(obj,prev) { prev.csum += obj.c; },
            initial: { csum: 0 }
            });
key: Fields to group by.
reduce: The reduce function aggregates (reduces) the objects iterated. Typical operations of a reduce function include summing and counting. reduce takes two arguments: the current document being iterated over and the aggregation counter object. In the example above, these arguments are named obj and prev.
initial: initial value of the aggregation counter object.
cond: An optional condition that must be true for a row to be considered. This is essentially a find() query expression object. If null, the reduce function will run against all rows in the collection.

详细的你可以看官网
javascript:lnkchk('noitagerggA%2fSCOD%2fyalpsid%2fgro.bdognom.www%2f%2f%3aptth');