如何在MongoDB中获取数组交集的数据？
对于MongoDB中的数组交互，请使用中的$setIntersectionaggregate()。让我们创建一个包含文档的集合-
> db.demo625.insertOne(
... {
... Name: "John",
... Marks: [56,98,60]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5e9ab8e16c954c74be91e6aa")
}
> db.demo625.insertOne(
... {
... Name: "John",
... Marks: [110,56,72]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5e9ab8e26c954c74be91e6ab")
}
> db.demo625.insertOne(
... {
... Name: "Chris",
... Marks: [90,91]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5e9ab8e26c954c74be91e6ac")
}
> db.demo625.insertOne(
... {
... Name: "Robert",
... Marks: [60,75]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5e9ab8e26c954c74be91e6ad")
}在find()方法的帮助下显示集合中的所有文档-
> db.demo625.find();
这将产生以下输出-
{ "_id" : ObjectId("5e9ab8e16c954c74be91e6aa"), "Name" : "John", "Marks" : [ 56, 98, 60 ] }
{ "_id" : ObjectId("5e9ab8e26c954c74be91e6ab"), "Name" : "John", "Marks" : [ 110, 56, 72 ] }
{ "_id" : ObjectId("5e9ab8e26c954c74be91e6ac"), "Name" : "Chris", "Marks" : [ 90, 91 ] }
{ "_id" : ObjectId("5e9ab8e26c954c74be91e6ad"), "Name" : "Robert", "Marks" : [ 60, 75 ] }以下是在MongoDB中获取数组交集数据的查询-
> db.demo625.aggregate([
...
...
... { "$project": {
... "Name": 1,
... "Marks": {
... "$setIntersection": [ "$Marks", [56,98,60] ]
... }
... }}
... ])这将产生以下输出-
{ "_id" : ObjectId("5e9ab8e16c954c74be91e6aa"), "Name" : "John", "Marks" : [ 56, 60, 98 ] }
{ "_id" : ObjectId("5e9ab8e26c954c74be91e6ab"), "Name" : "John", "Marks" : [ 56 ] }
{ "_id" : ObjectId("5e9ab8e26c954c74be91e6ac"), "Name" : "Chris", "Marks" : [ ] }
{ "_id" : ObjectId("5e9ab8e26c954c74be91e6ad"), "Name" : "Robert", "Marks" : [ 60 ] }