mongodb中的最大值和最小值 [英] Max and min in mongodb

问题描述

我有以下类似DB的条目:

I have the below DB like entries :

我的插入查询

 db.collection.insert({company:"C3",model:"M3",price:55600,discount:9,resolution:"100X700",connectivity:"hdmi2",warranty:"3",image:"image2.jpg",size:50,display:"lcd",brand:"Brand4",functionality:"functionality2"});

有超过2000个条目，我正尝试找出整个集合中的最高价和最低价，如下所示:

there are more than 2000 entries , I am trying to find out the max and min price in the whole collection like below :

db.collection.find({max:{$max:"$price"}, min:{$min:"$price"}});

想要输出为{max:2000，min:5000}，请帮助.谢谢

want the output as {max:2000,min:5000}, please help .thanks

推荐答案

您需要使用 .aggregate() 方法使其起作用.

You need to use the .aggregate() method for it to work.

db.collection.aggregate([ 
    { "$group": { 
        "_id": null,
        "max": { "$max": "$price" }, 
        "min": { "$min": "$price" } 
    }}
])

_id字段在 阶段，然后找到 max / min 值的价格对于非特殊组的孔收集，需要将其设置为 null ，否则查询将仅返回每个组的最大/最小

The _id field is mandatory in the $group stage and to find the max/min values for price for the hole collection not for special group it needs to be set to null otherwise the query will only return max/min for each group

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