“MongoDB 基础教程”实验报告

查询、索引与聚合

获取添加的数据

> db.users.find().pretty()
{
"_id" : ObjectId("5b79047abd2b073cdefed380"),
"name" : "marry",
"age" : 23,
"status" : "A",
"amount" : 250,
"coust_id" : "A123"
}
{
"_id" : ObjectId("5b790472bd2b073cdefed37f"),
"age" : 18,
"amount" : 200,
"coust_id" : "A123",
"name" : "tom",
"status" : "A"
}
{
"_id" : ObjectId("5b790955bd2b073cdefed381"),
"name" : "joe",
"age" : 18,
"amount" : 200,
"coust_id" : "B123",
"status" : "B"
}
{
"_id" : ObjectId("5b790981bd2b073cdefed382"),
"name" : "lee",
"age" : 20,
"amount" : 100,
"coust_id" : "A122",
"status" : "A"
}
copy

查找状态A, 以A123的分组,计算金额总和

> db.users.aggregate([{$match:{status:'A'}},{$group:{'_id':"$coust_id", total:{$sum:"$amount"}}}])
{
"result" : [
{
"_id" : "A122",
"total" : 100
},
{
"_id" : "A123",
"total" : 450
}
],
"ok" : 1
}
copy
最新评论
暂无评论~