MongoDB $or 运算符

MongoDB $or 运算符 介绍

MongoDB 提供了多种逻辑查询运算符。$or 运算符就是这些运算符之一。$or 运算符对一个或多个表达式的数组执行逻辑“或”运算。此运算符仅用于检索与数组中至少一个给定表达式匹配的文档。

$OR 运算符用于在单个查询中查找多个表达式，该查询仅需要文档中的一个匹配条件。$or 运算符可以使用多个键和值。

1. 用户可以根据需要在 find()、update() 等方法中使用此运算符。
2. 您还可以将此运算符用于地理空间查询、排序操作和文本查询。

MongoDB $or 运算符 语法

{ $or: [ { Expression 1 }, { Expression 2 }, ..., { Expression N } ] }  

MongoDB $or 运算符 例子

在以下示例中，我们正在使用：

Database: Yiidian
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：MongoDB 逻辑 $or 运算符：

在此示例中，我们仅检索课程为“MCA”或 batch_year 为 2018 的学生的数据。

>db.student.find({$ or : [{Course :  "MCA" }, {batch_year : 2018}]}).pretty()  

>db.sutdent.find({$or: [{Course : "MCA"}, {batch_year : 2018}]}).pretty()
{
           "_id" : ObjectId("56254d4fdf2222265r4g12ds3d65f"),
           "name" : "Mick",
           "Coruse" : "btech",
           "batch_year" : 2018,
           "language" : ["c++", "java", "python"],
           "personal_details" : 
                     {
                      "Father_name" : "Jonny",
                      "phone_no" : 8895321456,
                      "age" : 23,
                      "gender" : "Male",
                      "City" : "NewYork",
                     }            
}
{
           "_id" : ObjectId("56254d4fdf2222265r4g12ds3d655"),
           "name" : "Jonny",
           "Coruse" : "MCA",
           "batch_year" : 2019,
           "language" : ["C#", "java", "PHP"],
           "personal_details" : 
                     {
                      "Father_name" : "Thomas",
                      "phone_no" : 7845123698,
                      "age" : 24,
                      "gender" : "Male",
                      "City" : "London",
                     }          
}

示例 2：MongoDB 逻辑 $or 运算符（检索嵌入文档中的数据）：

在此示例中，我们仅检索城市为“伦敦”或年龄为 20 岁的学生文档。

>db.student.find({$ or : [{ "personal.age" : 20}, { "personal.City" :  "London" }]}).pretty()  

输出结果为：

>db.student.find({$or: [{"personal.age": 20}, {"personal.City": "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 3：使用 $or 运算符匹配数组中的值：

在此示例中，我们仅检索与给定数组中至少一个值匹配的学生文档。

>db.student.find({$ or : [{language: {$ in : [ "c++" ,  "java" ,  "python" ]}}]}).pretty()  

输出结果为：

>db.student.find({$or: [{language: {$in: ["c++", "java", "HTML"]}}]}).pretty()
{
           "_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("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",
                     }           
}