在MongoDB中需要按小时和$ avg进行汇总
aggregate()在MongoDB中使用。它为集合中的数据计算聚合值。让我们创建一个包含文档的集合-
> db.demo544.insertOne({"DueTime":new ISODate("2020-01-10 12:10:20"),Amount:100});{
"acknowledged" : true,
"insertedId" : ObjectId("5e8e1f029e5f92834d7f05ce")
}
> db.demo544.insertOne({"DueTime":new ISODate("2020-01-12 12:00:00"),Amount:500});{
"acknowledged" : true,
"insertedId" : ObjectId("5e8e1f089e5f92834d7f05cf")
}
> db.demo544.insertOne({"DueTime":new ISODate("2020-01-12 12:10:20"),Amount:900});{
"acknowledged" : true,
"insertedId" : ObjectId("5e8e1f109e5f92834d7f05d0")
}在find()方法的帮助下显示集合中的所有文档-
> db.demo544.find();
这将产生以下输出-
{ "_id" : ObjectId("5e8e1f029e5f92834d7f05ce"), "DueTime" : ISODate("2020-01-10T12:10:20Z"), "Amount" : 100 }
{ "_id" : ObjectId("5e8e1f089e5f92834d7f05cf"), "DueTime" : ISODate("2020-01-12T12:00:00Z"), "Amount" : 500 }
{ "_id" : ObjectId("5e8e1f109e5f92834d7f05d0"), "DueTime" : ISODate("2020-01-12T12:10:20Z"), "Amount" : 900 }以下是按小时和$avg汇总的查询-
> db.demo544.aggregate( { "$group": { "_id": { "$hour": "$dueTime" }, "Amount": { "$avg": "$Amount" } }} )这将产生以下输出-
{ "_id" : null, "Amount" : 500 }