在MongoDB中将数组项分组并获得具有相似价格的产品计数？

2026-06-05 1 花语

要对数组项进行分组，请使用$group和$sort。让我们创建一个包含文档的集合-

> db.demo566.insertOne( ... { ... ... "ProductInformation" : [ ... { ... "ProductName" : "Product-1", ... "ProductPrice" :100 ... }, ... { ... "ProductName" : "Product-2", ... "ProductPrice" :1100 ... }, ... { ... "ProductName" : "Product-3", ... "ProductPrice" :100 ... }, ... { ... "ProductName" : "Product-4", ... "ProductPrice" :1100 ... }, ... { ... "ProductName" : "Product-5", ... "ProductPrice" :100 ... } ... ] ... ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5e908e2339cfeaaf0b97b57a") }

在find()方法的帮助下显示集合中的所有文档-

> db.demo566.find();

这将产生以下输出-

{ "_id" : ObjectId("5e908e2339cfeaaf0b97b57a"), "ProductInformation" : [ { "ProductName" : "Product-1", "ProductPrice" : 100 }, { "ProductName" : "Product-2", "ProductPrice" : 1100 }, { "ProductName" : "Product-3", "ProductPrice" : 100 }, { "ProductName" : "Product-4", "ProductPrice" : 1100 }, { "ProductName" : "Product-5", "ProductPrice" : 100 } ] }

以下是对数组项进行分组的查询-

> db.demo566.aggregate([ ... { ... "$unwind": "$ProductInformation" ... }, ... { ... "$group": { ... "_id": "$ProductInformation.ProductPrice", ... "Value": { "$sum" : 1 } ... } ... }, ... { "$sort": { "_id" :1 } } ... ])

这将产生以下输出-

{ "_id" : 100, "Value" : 3 } { "_id" : 1100, "Value" : 2 }