MongoDB查询要按几个数组元素过滤？
要按几个数组元素过滤，请使用$elemMatch。让我们创建一个包含文档的集合-
> db.demo87.insertOne(
... {
... id:101,
... "Details": [
... {
... "EmployeeName": "Chris",
... "Salary": 45000
... },
... {
... "EmployeeName": "David",
... "Salary": 50000
... }
... ]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5e2c113871bf0181ecc422ab")
}
> db.demo87.insertOne(
... {
... id:102,
... "Details": [
... {
... "EmployeeName": "Chris",
... "Salary": 65000
... },
... {
... "EmployeeName": "Mike",
... "Salary": 100000
... }
... ]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5e2c114371bf0181ecc422ac")
}在find()方法的帮助下显示集合中的所有文档-
> db.demo87.find();
这将产生以下输出-
{
"_id" : ObjectId("5e2c113871bf0181ecc422ab"), "id" : 101, "Details" : [
{ "EmployeeName" : "Chris", "Salary" : 45000 },
{ "EmployeeName" : "David", "Salary" : 50000 }
]
}
{
"_id" : ObjectId("5e2c114371bf0181ecc422ac"), "id" : 102, "Details" : [
{ "EmployeeName" : "Chris", "Salary" : 65000 },
{ "EmployeeName" : "Mike", "Salary" : 100000 }
]
}以下是按几个数组元素过滤的查询-
> db.demo87.find({ Details: { $elemMatch: { "EmployeeName": 'Chris', "Salary": 65000 }}});这将产生以下输出-
{
"_id" : ObjectId("5e2c114371bf0181ecc422ac"), "id" : 102, "Details" : [
{ "EmployeeName" : "Chris", "Salary" : 65000 },
{ "EmployeeName" : "Mike", "Salary" : 100000 }
]
}