Filter record from collection “OperationSession”, sort by “WorldId” descending, then group by “WorldId”, then pick first record from each group, then sort result: Way #1: db.getCollection('OperationSession').aggregate( [ { "$match": {"ActivityId":74,"GameId":2109} }, { "$sort":{ "CreateTime" : -1} }, { "$group": { _id:"$WorldId", SessionId:{"$first": "$_id" }, GameId:{"$first": "$GameId" }, WorldId:{"$first": "$WorldId" }, ActivityId:{"$first": "$ActivityId" }, Type:{"$first": "$Type" …
Tag: mongodb
MongoDB中使用$rename指令修改字段名
如下所示：把collection Policy中的Type为1的所有document的UserID字段修改为UserName, multi为true表明修改所有记录，upsert为false表明记录不存在则不创建： db.getCollection('Policy').update({"Type":1},{$rename:{'UserID': 'UserName'}},{"multi" : true, "upsert" : false}) 参考：https://docs.mongodb.com/manual/reference/operator/update/rename/