MongoDB $ elemMatch匹配文档
让我们创建一个包含文档的集合-
> db.demo313.insertOne({"_id":100,"details":[{"Name":"Chris","Age":24}]});
{ "acknowledged" : true, "insertedId" : 100 }
> db.demo313.insertOne({"_id":101,"details":[{"Name":"David","Age":22}]});
{ "acknowledged" : true, "insertedId" : 101 }
> db.demo313.insertOne({"_id":102,"details":[{"Name":"Mike","Age":25}]});
{ "acknowledged" : true, "insertedId" : 102 }在find()方法的帮助下显示集合中的所有文档-
> db.demo313.find();
这将产生以下输出-
{ "_id" : 100, "details" : [ { "Name" : "Chris", "Age" : 24 } ] }
{ "_id" : 101, "details" : [ { "Name" : "David", "Age" : 22 } ] }
{ "_id" : 102, "details" : [ { "Name" : "Mike", "Age" : 25 } ] }以下是在MongoDB中将文件与$elemMatch匹配的查询-
db.demo313.find({_id:101},{details: { $elemMatch: { Age: 22 } } } );这将产生以下输出-
{ "_id" : 101, "details" : [ { "Name" : "David", "Age" : 22 } ] }