在MongoDB中实现多个条件？
首先让我们创建一个包含文档的集合-
> db.multipleConditionDemo.insertOne({"_id":1,"Name":"John"});
{ "acknowledged" : true, "insertedId" : 1 }
> db.multipleConditionDemo.insertOne({"_id":2,"Name":"Carol"});
{ "acknowledged" : true, "insertedId" : 2 }
> db.multipleConditionDemo.insertOne({"_id":3,"Name":"Sam"});
{ "acknowledged" : true, "insertedId" : 3 }
> db.multipleConditionDemo.insertOne({"_id":4,"Name":"David"});
{ "acknowledged" : true, "insertedId" : 4 }以下是在find()方法的帮助下显示集合中所有文档的查询-
> db.multipleConditionDemo.find().pretty();
这将产生以下输出-
{ "_id" : 1, "Name" : "John" }
{ "_id" : 2, "Name" : "Carol" }
{ "_id" : 3, "Name" : "Sam" }
{ "_id" : 4, "Name" : "David" }以下是在WHERE子句中实现多个条件的查询-
> db.multipleConditionDemo.remove({ $or: [ { _id: 2 }, { _id: 3 } ] });
WriteResult({ "nRemoved" : 2 })让我们再次检查上述集合中的文档-
> db.multipleConditionDemo.find().pretty();
这将产生以下输出-
{ "_id" : 1, "Name" : "John" }
{ "_id" : 4, "Name" : "David" }