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db.getSiblingDB()

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Definition定义

db.getSiblingDB(<database>)
Parameter参数Type类型Description描述
databasestringThe name of a MongoDB database.MongoDB数据库的名称。
Returns:返回值：A database object.数据库对象。

Used to return another database without modifying the db variable in the shell environment.用于在不修改shell环境中的db变量的情况下返回另一个数据库。

Example实例

You can use db.getSiblingDB() as an alternative to the use <database> helper. 您可以使用db.getSiblingDB()作为use <database>助手的替代方法。This is particularly useful when writing scripts using mongosh where the use helper is not available.

Consider a MongoDB instance with two databases, users and records. The active collection is a part of the users database. The requests collection is a part of the records database.

Specify a Database指定数据库

This operation sets the db object to point to the database named users, and then returns a document count for the active collection.

db = db.getSiblingDB('users')
db.active.countDocuments()

Use Multiple Databases

You can create multiple db objects, that refer to different databases, as in the following sequence of operations:

users = db.getSiblingDB('users')
records = db.getSiblingDB('records')

users.active.countDocuments()
users.active.findOne()

records.requests.countDocuments()
records.requests.findOne()

This operation creates two db objects. Each db object refers to a different database, users or records.

For each database, the query returns:

from a collection in that database.