mongodb中如何删除列?
刚用mongodb, 比如有个collection内容如下:{ "_id" : ObjectId("502888b73f8a7cc3ffbdede8"), "id" : 1, "nam" : 210 }
{ "_id" : ObjectId("502887403f8a7cc3ffbdede7"), "id" : 3, "nam" : "t3", "name" : 10 }
{ "_id" : ObjectId("50289af13f8a7cc3ffbdede9"), "id" : 2, "nam" : 500 }
怎么删除其中的name列?帮助文档中没找到删除列的关键字 > use user ###假设集合是user
switched to db user
> i={ "_id" : ObjectId("502887403f8a7cc3ffbdede7"), "id" : 3, "nam" : "t3", "name" : 10 }
{
"_id" : ObjectId("502887403f8a7cc3ffbdede7"),
"id" : 3,
"nam" : "t3",
"name" : 10
}
> db.user.insert(i) ####将你的数据加进去,这里我只加你要修改的那条
> db.user.find() ####查看数据是否插入进去
{ "_id" : ObjectId("502887403f8a7cc3ffbdede7"), "id" : 3, "nam" : "t3", "name" : 10 }
> someone=db.user.findOne({"id":3}) ###将你要修改的文档找出来,并赋给someone
{
"_id" : ObjectId("502887403f8a7cc3ffbdede7"),
"id" : 3,
"nam" : "t3",
"name" : 10
}
> delete someone.name####删除someone中你想删除在列(name)
true
> someone ###可以查看someone已经修改
{ "_id" : ObjectId("502887403f8a7cc3ffbdede7"), "id" : 3, "nam" : "t3" }
> db.user.find() ###但数据库中的文档没变
{ "_id" : ObjectId("502887403f8a7cc3ffbdede7"), "id" : 3, "nam" : "t3", "name" : 10 }
> db.user.update({id:3},someone) ###更新数据库中的文档
> db.user.find()###查看文档,虽然有点烦,但终于还是达到了你的目标
{ "_id" : ObjectId("502887403f8a7cc3ffbdede7"), "id" : 3, "nam" : "t3" }
>
最近学了修改器,发现删除键太简单了,之前的操作简直让我害羞啊......
> db.name.insert({id:3,nam:"t3",name:10})
> db.name.find()
{ "_id" : ObjectId("505a570bf67c1b9a341caefa"), "id" : 3, "nam" : "t3", "name" : 10 }
> db.name.update({"id" : 3},{$unset:{"name" : 10}})
> db.name.find()
{ "_id" : ObjectId("505a570bf67c1b9a341caefa"), "id" : 3, "nam" : "t3" } 非常感谢:))
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