极客笔记MongoDB $in 运算符
MongoDB 提供不同类型的逻辑查询运算符，$in 运算符是其中之一。$in 运算符用于选择字段值等于数组中给定值任何一个的文档。根据需求，你可以在诸如 find()、update() 等方法中使用该运算符。
语法
{ field: { $in: [<value 1>, <value 2>, ... <value N> ] } }
示例
在下面的示例中，我们正在处理：
Database: JavaTpoint
Collection: student
Document: Five documents that contain the details of the students
>db.student.find()
{
"_id" : ObjectId("56254d4fdf2222265r4g12ds3d65f"),
"name" : "Mick",
"Course" : "btech",
"batch_year" : 2018,
"language" : ["c++", "java", "python"],
"personal_details" :
{
"Father_name" : "Jonny",
"phone_no" : 8895321456,
"age" : 23,
"gender" : "Male",
"City" : "NewYork",
}
}
{
"_id" : ObjectId("56254d4fdf2222265r4g12ds3d691"),
"name" : "Zoya",
"Course" : "BCA",
"batch_year" : 2020,
"language" : ["C#", "JavaScript"],
"personal_details" :
{
"Father_name" : "Henry",
"phone_no" : 9874563698,
"age" : 20,
"gender" : "Female",
"City" : "London",
}
}
{
"_id" : ObjectId("56254d4fdf2222265r4g12ds3d655"),
"name" : "Jonny",
"Course" : "MCA",
"batch_year" : 2019,
"language" : ["C#", "java", "PHP"],
"personal_details" :
{
"Father_name" : "Thomas",
"phone_no" : 7845123698,
"age" : 24,
"gender" : "Male",
"City" : "London",
}
}
{
"_id" : ObjectId("56254d4fdf2222265r4g12ds3d678"),
"name" : "Oliver",
"Course" : "BA",
"batch_year" : 2017,
"language" : ["c", "PHP"],
"personal_details" :
{
"Father_name" : "William",
"phone_no" : 9997845123,
"age" : 25,
"gender" : "Male",
"City" : "Liverpool",
}
}
{
"_id" : ObjectId("56254d4fdf2222265r4g12ds3d665"),
"name" : "Mia",
"Course" : "btech",
"batch_year" : 2020,
"language" : ["HTML", "CSS", "PHP"],
"personal_details" :
{
"Father_name" : "Leo",
"phone_no" : 6312547896,
"age" : 22,
"gender" : "Female",
"City" : "Manchester",
}
}
示例1：使用$in操作符匹配值
在此示例中，我们只检索名为Jonny或Mia的学生的数据。
>db.student.find({name: {$in: ["Jonny", "Mia"]}}).pretty()
输出：
>db.student.find({name: {$in: ["Jonny", "Mia"]}}).pretty()
{
"_id" : ObjectId("56254d4fdf2222265r4g12ds3d655"),
"name" : "Jonny",
"Course" : "MCA",
"batch_year" : 2019,
"language" : ["C#", "java", "PHP"],
"personal_details" :
{
"Father_name" : "Thomas",
"phone_no" : 7845123698,
"age" : 24,
"gender" : "Male",
"City" : "London",
}
}
{
"_id" : ObjectId("56254d4fdf2222265r4g12ds3d665"),
"name" : "Mia",
"Course" : "btech",
"batch_year" : 2020,
"language" : ["HTML", "CSS", "PHP"],
"personal_details" :
{
"Father_name" : "Leo",
"phone_no" : 6312547896,
"age" : 22,
"gender" : "Female",
"City" : "Manchester",
}
}
示例2：使用$in运算符在数组中匹配值
在本示例中，我们只检索与以下其中之一相关的学生数据：JavaScript或CSS。
>db.student.find({language: {$in: ["JavaScript", "CSS"]}}).pretty()
输出结果：
>db.student.find({language: {$in: ["JavaScript", "CSS"]}}).pretty()
{
"_id" : ObjectId("56254d4fdf2222265r4g12ds3d691"),
"name" : "Zoya",
"Course" : "BCA",
"batch_year" : 2020,
"language" : ["C#", "JavaScript"],
"personal_details" :
{
"Father_name" : "Henry",
"phone_no" : 9874563698,
"age" : 20,
"gender" : "Female",
"City" : "London",
}
}
{
"_id" : ObjectId("56254d4fdf2222265r4g12ds3d665"),
"name" : "Mia",
"Course" : "btech",
"batch_year" : 2020,
"language" : ["HTML", "CSS", "PHP"],
"personal_details" :
{
"Father_name" : "Leo",
"phone_no" : 6312547896,
"age" : 22,
"gender" : "Female",
"City" : "Manchester",
}
}
示例3：MongoDB逻辑运算符$or（检索嵌入文档中的数据）
在这个示例中，我们只检索那些城市是“伦敦”的学生文档。
>db.student.find({"personal.City": {$in: ["London"]}}).pretty()
输出结果：
>db.student.find({"personal.City": {$in: ["London"]}}).pretty()
{
"_id" : ObjectId("56254d4fdf2222265r4g12ds3d691"),
"name" : "Zoya",
"Course" : "BCA",
"batch_year" : 2020,
"language" : ["C#", "JavaScript"],
"personal_details" :
{
"Father_name" : "Henry",
"phone_no" : 9874563698,
"age" : 20,
"gender" : "Female",
"City" : "London",
}
}
{
"_id" : ObjectId("56254d4fdf2222265r4g12ds3d655"),
"name" : "Jonny",
"Course" : "MCA",
"batch_year" : 2019,
"language" : ["C#", "java", "PHP"],
"personal_details" :
{
"Father_name" : "Thomas",
"phone_no" : 7845123698,
"age" : 24,
"gender" : "Male",
"City" : "London",
}
}
示例4：使用$in操作符更新数据
在这个示例中，我们使用update()方法和in和set操作符，将一个新的字段-值对（Pending_fees: 88.5）添加到Mick、Zoya和Mia的文档中。
>db.student.update({name: {in: ["Mick", "Zoya", "Mia"]}}, {set: {Pending_fees: 12000}})
注意：默认情况下，update()方法一次只能更新一个文档。因此，在这个示例中，update()方法只会更新与给定条件匹配的第一个文档。如果你想要更新多个文档，请将其multi参数的值设为true。
输出：
>db.student.update({name: {in: ["Mick", "Zoya", "Mia"]}}, {set: {Pending_fees: 12000}})
{
"_id" : ObjectId("56254d4fdf2222265r4g12ds3d65f"),
"name" : "Mick",
"Course" : "btech",
"batch_year" : 2018,
"language" : ["c++", "java", "python"],
"personal_details" :
{
"Father_name" : "Jonny",
"phone_no" : 8895321456,
"age" : 23,
"gender" : "Male",
"City" : "NewYork",
}
"Pending_fees" : 12000
}