在 MongoDB 中只检索一个指定条件的文档
让我们创建一个包含文档的集合-
> db.demo596.insertOne({_id:1,"FirstName":"John","LastName":"Smith"});
{ "acknowledged" : true, "insertedId" : 1 }
> db.demo596.insertOne({_id:2,"FirstName":"John","LastName":"Doe"});
{ "acknowledged" : true, "insertedId" : 2 }
> db.demo596.insertOne({_id:3,"FirstName":"Chris","LastName":"Brown"});
{ "acknowledged" : true, "insertedId" : 3 }
> db.demo596.insertOne({_id:4,"FirstName":"David","LastName":"Miller"});
{ "acknowledged" : true, "insertedId" : 4 }在find()方法的帮助下显示集合中的所有文档-
> db.demo596.find();
这将产生以下输出-
{ "_id" : 1, "FirstName" : "John", "LastName" : "Smith" }
{ "_id" : 2, "FirstName" : "John", "LastName" : "Doe" }
{ "_id" : 3, "FirstName" : "Chris", "LastName" : "Brown" }
{ "_id" : 4, "FirstName" : "David", "LastName" : "Miller" }这是仅检索单个文档的查询-
> db.demo596.findOne({"FirstName":"John"});这将产生以下输出-
{ "_id" : 1, "FirstName" : "John", "LastName" : "Smith" }