Mongodb group and sort

Question

How can I translate the following Sql query for Mongo?:

select a,b,sum(c) csum from coll wh         


        

Answer 1

Adding to previous answers, if you want to sort on the sum (the result of the aggregate) instead of on the actual column, you can do this:

db.your_collection.aggregate([
    {
        $group: {_id: "$your_document_name", count: {$sum: 1}}
    }, 
    {
        $sort: {"count":-1}
    }
])

This would be the equivalent of the following standard-SQL-ish syntax:

select col_a, count(col_a) as b
from table
group by col_a
order by b desc