删除

定义

delete

The delete command removes documents from a collection. A single delete command can contain multiple delete specifications. The delete methods provided by the MongoDB drivers use this command internally.

5.0 版本中的更改。

提示

In mongosh, this command can also be run through the deleteOne(), deleteMany(), and findOneAndDelete() helper methods.

辅助方法对 mongosh 用户来说很方便，但它们返回的信息级别可能与数据库命令不同。如果不追求方便或需要额外的返回字段，请使用数据库命令。

返回：	包含操作状态的文档。有关详细信息，请参阅输出。

兼容性

此命令可用于以下环境中托管的部署：

• MongoDB Atlas：用于云中 MongoDB 部署的完全托管服务

• MongoDB Enterprise：基于订阅、自我管理的 MongoDB 版本

• MongoDB Community：源代码可用、免费使用且可自行管理的 MongoDB 版本

语法

该命令具有以下语法：

 db.runCommand(
    {
      delete: <collection>,
      deletes: [
         {
           q : <query>,
           limit : <integer>,
           collation: <document>,
           hint: <document|string>
         },
         ...
      ],
      comment: <any>,
      let: <document>, // Added in MongoDB 5.0
      ordered: <boolean>,
      writeConcern: { <write concern> },
      maxTimeMS: <integer>
   }
)

命令字段

该命令接受以下字段：

{
  <variable_name_1>: <expression_1>,
  ...,
  <variable_name_n>: <expression_n>
}

Each element of the deletes array contains the following fields:

collation: {
   locale: <string>,
   caseLevel: <boolean>,
   caseFirst: <string>,
   strength: <int>,
   numericOrdering: <boolean>,
   alternate: <string>,
   maxVariable: <string>,
   backwards: <boolean>
}

行为

示例

db.runCommand(
   {
      delete: "orders",
      deletes: [ { q: { status: "D" }, limit: 1 } ]
   }
)

{ "ok" : 1, "n" : 1 }

db.runCommand(
   {
      delete: "orders",
      deletes: [ { q: { status: "D" }, limit: 0 } ],
      writeConcern: { w: "majority", wtimeout: 5000 }
   }
)

{ "ok" : 1, "n" : 13 }

db.runCommand(
   {
      delete: "orders",
      deletes: [ { q: { }, limit: 0 } ],
      writeConcern: { w: "majority", wtimeout: 5000 }
   }
)

{ "ok" : 1, "n" : 35 }

db.runCommand(
   {
      delete: "orders",
      deletes: [
         { q: { status: "D" }, limit: 0 },
         { q: { cust_num: 99999, item: "abc123", status: "A" }, limit: 1 }
      ],
      ordered: false,
      writeConcern: { w: 1 }
   }
)

{ "ok" : 1, "n" : 21 }

{ _id: 1, category: "café", status: "A" }
{ _id: 2, category: "cafe", status: "a" }
{ _id: 3, category: "cafE", status: "a" }

db.runCommand({
   delete: "myColl",
   deletes: [
     { q: { category: "cafe", status: "a" }, limit: 0, collation: { locale: "fr", strength: 1 } }
   ]
})

db.members.insertMany([
   { "_id" : 1, "member" : "abc123", "status" : "P", "points" :  0,  "misc1" : null, "misc2" : null },
   { "_id" : 2, "member" : "xyz123", "status" : "A", "points" : 60,  "misc1" : "reminder: ping me at 100pts", "misc2" : "Some random comment" },
   { "_id" : 3, "member" : "lmn123", "status" : "P", "points" :  0,  "misc1" : null, "misc2" : null },
   { "_id" : 4, "member" : "pqr123", "status" : "D", "points" : 20,  "misc1" : "Deactivated", "misc2" : null },
   { "_id" : 5, "member" : "ijk123", "status" : "P", "points" :  0,  "misc1" : null, "misc2" : null },
   { "_id" : 6, "member" : "cde123", "status" : "A", "points" : 86,  "misc1" : "reminder: ping me at 100pts", "misc2" : "Some random comment" }
])

db.members.createIndex( { status: 1 } )
db.members.createIndex( { points: 1 } )

db.runCommand({
   delete: "members",
   deletes: [
     { q: { "points": { $lte: 20 }, "status": "P" }, limit: 0, hint: { status: 1 } }
   ]
})

db.runCommand(
   {
     explain: {
       delete: "members",
       deletes: [
         { q: { "points": { $lte: 20 }, "status": "P" }, limit: 0, hint: { status: 1 } }
       ]
     },
     verbosity: "queryPlanner"
   }
)

db.cakeFlavors.insertMany( [
   { _id: 1, flavor: "chocolate" },
   { _id: 2, flavor: "strawberry" },
   { _id: 3, flavor: "cherry" }
] )

db.runCommand( {
   delete: db.cakeFlavors.getName(),
   deletes: [ {
      q: { $expr: { $eq: [ "$flavor", "$$targetFlavor" ] } },
      limit: 1
   } ],
   let : { targetFlavor: "strawberry" }
} )

输出

返回的文档包含以下字段的子集：

delete.ok

命令的状态。

delete.n

The number of documents deleted.

delete.writeErrors

An array of documents that contains information regarding any error encountered during the delete operation. The writeErrors array contains an error document for each delete statement that errors.

Each error document contains the following information:

delete.writeErrors.index

An integer that identifies the delete statement in the deletes array, which uses a zero-based index.

delete.writeErrors.code

标识错误的整数值。

delete.writeErrors.errmsg

错误描述。

delete.writeConcernError

描述与写关注（write concern）相关的错误的文档。

在版本7.0.6 中进行了更改：（也适用于 6.0.14和5.0.30 ）：当delete 在mongos 上执行时，即使发生一个或多个写入错误，也始终会报告写关注（write concern）错误。在以前的版本中，发生写入错误可能会导致 不报告写关注（writedelete concern）错误。

The writeConcernError documents contian the following fields:

delete.writeConcernError.code

一个整数值，用于标识写关注错误原因。

delete.writeConcernError.errmsg

写关注错误原因的描述。

delete.writeConcernError.errInfo.writeConcern

用于相应操作的写关注对象。有关写关注对象字段的信息，请参阅写关注规范。

写关注对象还可能包含以下字段，指示写关注的来源：

delete.writeConcernError.errInfo.writeConcern.provenance

一个表示写关注来源（称为写关注provenance）的字符串值。下表显示该字段的可能值及其有效位数：

来源	说明
clientSupplied	应用程序中指定了写关注。
customDefault	写入关注源自自定义的默认值。请参阅 setDefaultRWConcern。
getLastErrorDefaults	写关注源自副本集的 settings.getLastErrorDefaults 字段。
implicitDefault	在没有所有其他写入关注规范的情况下，写入关注源自服务器。

The following is an example document returned for a successful delete command:

{ ok: 1, n: 1 }

The following is an example document returned for a delete command that encountered an error because it specified a non-existent index in the hint field:

{
  n: 0,
  writeErrors: [
    {
      index: 0,
      code: 2,
      errmsg: 'error processing query: ns=test.products: hat $eq "bowler"\n' +
        'Sort: {}\n' +
        'Proj: {}\n' +
        ' planner returned error :: caused by :: hint provided does not correspond to an existing index'
    }
  ],
  ok: 1
}