在 MongoDB 中删除字段和值?
mongodbdatabasebig data analytics更新于 2026/1/19 2:22:17
要删除 MongoDB 字段和值，可以使用 $unset 运算符。首先，我们创建一个包含文档的集合。 −
> db.deleteFieldDemo.insertOne({"FirstName":"John","LastName":"Smith"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cb9fb767219729fde21ddad")
}
> db.deleteFieldDemo.insertOne({"FirstName":"David","LastName":"Miller"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cb9fb837219729fde21ddae")
}
> db.deleteFieldDemo.insertOne({"FirstName":"Carol","LastName":"Taylor"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cb9fb8d7219729fde21ddaf")
}
以下是使用 find() 方法显示集合中的所有文档的查询 −
> db.deleteFieldDemo.find().pretty();
这将产生以下输出 −
{
"_id" : ObjectId("5cb9fb767219729fde21ddad"),
"FirstName" : "John",
"LastName" : "Smith"
}
{
"_id" : ObjectId("5cb9fb837219729fde21ddae"),
"FirstName" : "David",
"LastName" : "Miller"
}
{
"_id" : ObjectId("5cb9fb8d7219729fde21ddaf"),
"FirstName" : "Carol",
"LastName" : "Taylor"
}
以下是删除具有值的字段的查询 −
> db.deleteFieldDemo.update(
... { FirstName: { $exists: true } },
... { $unset: { FirstName: 1 } },
... false,
... true
... );
WriteResult({ "nMatched" : 3, "nUpserted" : 0, "nModified" : 3 })
检查字段 FirstName 是否已从集合中删除 −
> db.deleteFieldDemo.find().pretty();
这将产生以下输出 −
{ "_id" : ObjectId("5cb9fb767219729fde21ddad"), "LastName" : "Smith" }
{ "_id" : ObjectId("5cb9fb837219729fde21ddae"), "LastName" : "Miller" }
{ "_id" : ObjectId("5cb9fb8d7219729fde21ddaf"), "LastName" : "Taylor" }
