MongoDB 通过多个数组项查找?
您可以使用$all运算符按多个数组项查找。为了理解这个概念,让我们用文档创建一个集合。
使用文档创建集合的查询如下-
> 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find()方法的帮助下显示集合中的所有文档。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" ] }
这是通过多个数组项查找的查询-
> db.findByMultipleArrayDemo.find({ StudentCoreSubject: { $all: ["Compiler", "Computer Networks"] }}).pretty();
以下是带有数组项“编译器”和“计算机网络”的输出显示记录-
{ "_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" ] }