MongoDB聚合简单查询

Question

我有这个样本MongoDB数据:

{"FirstName": "Bruce", "LastName": "Wayne", 
"Email": "[e-mail]"}
{"FirstName": "Lucius", "LastName": "Fox", 
"Email": "[e-mail]"}
{"FirstName": "Dick", "LastName": "Grayson", 
"Email": "[e-mail]"}

和我想要得到的并找到所有文档的计数

Answer 1

可以这样写:

db.col.aggregate([  {$match:{  "Bed Grade":4}}  , {  $group: {_id:{h:"$Hospital_code" ,d:"$Department" } , cnt:{$sum:1}} }  , {$match:{cnt:{$gt:5}}}  ])