MongoDB聚合以对具有相似ID的产品价格求和
您需要使用$group对具有指定_id表达式的文档进行分组。首先让我们创建一个包含文档的集合-
> db.aggreagateDemo.insertOne({"Product_Id":1,"ProductPrice":50});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e06d3c025ddae1f53b621d9")
}
> db.aggreagateDemo.insertOne({"Product_Id":2,"ProductPrice":100});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e06d3c625ddae1f53b621da")
}
> db.aggreagateDemo.insertOne({"Product_Id":2,"ProductPrice":500});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e06d3cb25ddae1f53b621db")
}
> db.aggreagateDemo.insertOne({"Product_Id":1,"ProductPrice":150});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e06d3d125ddae1f53b621dc")
}以下是在find()方法的帮助下显示集合中所有文档的查询-
> db.aggreagateDemo.find().pretty();
这将产生以下输出-
{
"_id" : ObjectId("5e06d3c025ddae1f53b621d9"),
"Product_Id" : 1,
"ProductPrice" : 50
}
{
"_id" : ObjectId("5e06d3c625ddae1f53b621da"),
"Product_Id" : 2,
"ProductPrice" : 100
}
{
"_id" : ObjectId("5e06d3cb25ddae1f53b621db"),
"Product_Id" : 2,
"ProductPrice" : 500
}
{
"_id" : ObjectId("5e06d3d125ddae1f53b621dc"),
"Product_Id" : 1,
"ProductPrice" : 150
}这是执行聚合和ID分组的查询-
> db.aggreagateDemo.aggregate([
... {
... $group: {
... _id: "$Product_Id",
... TotalValue:{$sum: "$ProductPrice"}
... }
... }
... ]
... );这将产生以下输出-
{ "_id" : 2, "TotalValue" : 600 }
{ "_id" : 1, "TotalValue" : 200 }