標籤:post aggregate count 年齡 函數 css body 總數 span
1、彙總函式
> db.userinfo.count()3> db.userinfo.find(){ "_id" : 1, "name" : "郭大爺", "sex" : "男", "age" : "80" }{ "_id" : 2, "name" : "郭老師", "sex" : "男", "age" : "不詳" }{ "_id" : 3, "name" : "郭少爺", "sex" : "男", "age" : "18" }
2、aggregate() 方法
我們先插入一些測試資料
{ "_id" : ObjectId("5abc960c684781cda6d38027"), "name" : "郭大爺", "sex" : "男", "age" : 80.0, "skil" : [ "PHP", "Js", "MySql", "Html", "Css" ]}{ "_id" : ObjectId("5abc960c684781cda6d38028"), "name" : "郭大爺", "sex" : "男", "age" : 60.0, "skil" : [ "PHP", "MySql" ]}{ "_id" : ObjectId("5abc960c684781cda6d38029"), "sex" : "女"}{ "_id" : ObjectId("5abc960c684781cda6d3802a"), "name" : "郭少爺", "sex" : "男", "age" : 18.0, "skil" : [ "Css", "Java", "Html" ]}
查詢一下所有人年齡的總和
db.userinfo.aggregate([ { $group : { _id : null, age_sum : { $sum : "$age" } }}])
結果
{ "_id" : null, "age_sum" : 158.0}
- 平均值
- 最小值
- 最大值
- 擷取第一個文檔
- 擷取最後一個文檔
MongoDB 彙總管道(aggregate)