1、group by多个key
db.testcol.aggregate(
{"$group": {_id:{card:"$card",account:"$account"}, "count": { "$sum": 1 } } }
)
2、group by having实现
mongodb 实现group by 多个key having count(*) >1
db.testcol.aggregate(
{"$group": {_id:{card:"$card",account:"$account"}, "count": { "$sum": 1 } } },
{"$match": {"_id" :{ "$ne" : null } , "count" : {"$gt": 1} } }
)