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法律研究使用 $in 查找多个数组项的 MongoDB？
您可以使用 $in 运算符来查找多个数组项。要理解此概念，我们创建一个带有文档的集合。
创建带有文档的集合的查询如下 -
>db.findByMultipleArrayDemo.insertOne({"StudentFirstName":"John","StudentLastName":"Smith",
"StudentCoreSubject":["Compiler","Operating System","Computer Networks"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c7ef07b559dd2396bcfbfc4")
}
>db.findByMultipleArrayDemo.insertOne({"StudentFirstName":"Carol","StudentLastName":"Taylor",
"StudentCoreSubject":["MongoDB","MySQL","SQL Server"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c7ef09d559dd2396bcfbfc5")
}
>db.findByMultipleArrayDemo.insertOne({"StudentFirstName":"Bob","StudentLastName":"Taylor",
"StudentCoreSubject":["MongoDB","MySQL","SQL Server"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c7ef0c7559dd2396bcfbfc6")
}
>db.findByMultipleArrayDemo.insertOne({"StudentFirstName":"David","StudentLastName":"Johnson",
"StudentCoreSubject":["Compiler","Operating System","Computer Networks"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c7ef0f2559dd2396bcfbfc7")
}在集合中，使用 find() 方法显示所有文档。查询如下 -
> db.findByMultipleArrayDemo.find().pretty();
以下是输出 -
{
"_id" : ObjectId("5c7ef07b559dd2396bcfbfc4"),
"StudentFirstName" : "John",
"StudentLastName" : "Smith",
"StudentCoreSubject" : [
"Compiler",
"Operating System",
"Computer Networks"
]
}
{
"_id" : ObjectId("5c7ef09d559dd2396bcfbfc5"),
"StudentFirstName" : "Carol",
"StudentLastName" : "Taylor",
"StudentCoreSubject" : [
"MongoDB",
"MySQL",
"SQL Server"
]
}
{
"_id" : ObjectId("5c7ef0c7559dd2396bcfbfc6"),
"StudentFirstName" : "Bob",
"StudentLastName" : "Taylor",
"StudentCoreSubject" : [
"MongoDB",
"MySQL",
"SQL Server"
]
}
{
"_id" : ObjectId("5c7ef0f2559dd2396bcfbfc7"),
"StudentFirstName" : "David",
"StudentLastName" : "Johnson",
"StudentCoreSubject" : [
"Compiler",
"Operating System",
"Computer Networks"
]
}使用 $in 运算符来查找多个数组项 -
> db.findByMultipleArrayDemo.find({ StudentCoreSubject: { $in: ["Compiler", "Computer Networks"] }}).pretty();以下是输出 -
{
"_id" : ObjectId("5c7ef07b559dd2396bcfbfc4"),
"StudentFirstName" : "John",
"StudentLastName" : "Smith",
"StudentCoreSubject" : [
"Compiler",
"Operating System",
"Computer Networks"
]
}
{
"_id" : ObjectId("5c7ef0f2559dd2396bcfbfc7"),
"StudentFirstName" : "David",
"StudentLastName" : "Johnson",
"StudentCoreSubject" : [
"Compiler",
"Operating System",
"Computer Networks"
]
}
更新于：30-7-2019
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