MongoDB中如何按数组值对集合排序
> db.demo577.insertOne(
... {
...
... "student": {
... "details": [
... {
... Name:"Chris",
... Score:45
... },
... {
... Name:"Bob",
... Score:33
... },
... {
... Name:"David",
... Score:48
... }
... ]
... }
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5e916ff1581e9acd78b427ff")
}在find()方法的帮助下显示集合中的所有文档-
> db.demo577.find();
这将产生以下输出-
{ "_id" : ObjectId("5e916ff1581e9acd78b427ff"), "student" : { "details" : [
{ "Name" : "Chris", "Score" : 45 },
{ "Name" : "Bob", "Score" : 33 },
{ "Name" : "David", "Score" : 48 }
] } }以下是按数组值对集合进行排序的查询-
> db.demo577.aggregate([
... {$unwind:"$student"},
... {$unwind:"$student.details"},
...
... {$sort:{"student.details.Score":-1}}
... ]);这将产生以下输出-
{ "_id" : ObjectId("5e916ff1581e9acd78b427ff"), "student" : { "details" : { "Name" : "David", "Score" : 48 } } }
{ "_id" : ObjectId("5e916ff1581e9acd78b427ff"), "student" : { "details" : { "Name" : "Chris", "Score" : 45 } } }
{ "_id" : ObjectId("5e916ff1581e9acd78b427ff"), "student" : { "details" : { "Name" : "Bob", "Score" : 33 } } }