如何从 MongoDB 集合中删除文档?
mongodbdatabasebig data analytics
要从 MongoDB 集合中删除文档，您需要使用 remove() 方法。语法如下:
db.yourCollectionName.remove(yourDeleteValue);
现在，让我们创建一个包含一些文档的集合。查询如下:
>db.deleteDocuments.insert({"UserId":1,"UserName":"Bob","UserTechnicalSubject":"Introducti on to PL/SQL"});
WriteResult({ "nInserted" : 1 })
>db.deleteDocuments.insert({"UserId":2,"UserName":"Carol","UserTechnicalSubject":"Introduction to MongoDB"});
WriteResult({ "nInserted" : 1 })
>db.deleteDocuments.insert({"UserId":3,"UserName":"John","UserTechnicalSubject":"Introduction to MySQL"});
WriteResult({ "nInserted" : 1 })
>db.deleteDocuments.insert({"UserId":4,"UserName":"Maxwell","UserTechnicalSubject":"Introduction to SQL Server"});
WriteResult({ "nInserted" : 1 })
您可以使用 find() 命令显示我们上面创建的集合中的所有文档。查询如下:
> db.deleteDocuments.find().pretty();
输出结果如下:
{
"_id" : ObjectId("5c6aaa9e64f3d70fcc9147ff"),
"UserId" : 1,
"UserName" : "Bob",
"UserTechnicalSubject" : "Introduction to PL/SQL"
}
{
"_id" : ObjectId("5c6aaab464f3d70fcc914800"),
"UserId" : 2,
"UserName" : "Carol",
"UserTechnicalSubject" : "Introduction to MongoDB"
}
{
"_id" : ObjectId("5c6aaac764f3d70fcc914801"),
"UserId" : 3,
"UserName" : "John",
"UserTechnicalSubject" : "Introduction to MySQL"
}
{
"_id" : ObjectId("5c6aaadc64f3d70fcc914802"),
"UserId" : 4,
"UserName" : "Maxwell",
"UserTechnicalSubject" : "Introduction to SQL Server"
}
删除单个文档
要从集合中删除单个文档，您需要使用 remove() 方法。查询如下。假设我们要删除带有"UserId:4"的文档:
>db.deleteDocuments.remove({"UserId":4,"UserName":"Maxwell","UserTechnicalSubject":"Int
roduction to SQL Server"});
WriteResult({ "nRemoved" : 2 })
现在，您可以借助 find() 命令显示所有文档，以验证"UserId:4"文档是否已成功删除。查询如下:
> db.deleteDocuments.find().pretty();
输出结果如下:
{
"_id" : ObjectId("5c6aaa9e64f3d70fcc9147ff"),
"UserId" : 1,
"UserName" : "Bob",
"UserTechnicalSubject" : "Introduction to PL/SQL"
}
{
"_id" : ObjectId("5c6aaab464f3d70fcc914800"),
"UserId" : 2,
"UserName" : "Carol",
"UserTechnicalSubject" : "Introduction to MongoDB"
}
{
"_id" : ObjectId("5c6aaac764f3d70fcc914801"),
"UserId" : 3,
"UserName" : "John",
"UserTechnicalSubject" : "Introduction to MySQL"
}
删除所有文档
要删除所有文档，您需要使用以下语法:
db.yourCollectionName.remove({ });
查询如下:
> db.deleteDocuments.remove({});
输出结果如下:
WriteResult({ "nRemoved" : 3 })
我们已经从集合 ‘deleteDocuments’ 中删除了所有文档:
