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sp_detach_db (Transact-SQL)

  • Article

Applies to: SQL Server

Detaches a database that is currently not in use from a server instance and, optionally, runs UPDATE STATISTICS on all tables before detaching.

For a replicated database to be detached, it must be unpublished. For more information, see the Remarks section later in this article.

Transact-SQL syntax conventions

Syntax

sp_detach_db
    [ [ @dbname = ] N'dbname' ]
    [ , [ @skipchecks = ] N'skipchecks' ]
    [ , [ @keepfulltextindexfile = ] N'keepfulltextindexfile' ]
[ ; ]

Arguments

[ @dbname = ] N'dbname'

The name of the database to be detached. @dbname is sysname, with a default of NULL.

[ @skipchecks = ] N'skipchecks'

Specifies whether to skip or run UPDATE STATISTICS. @skipchecks is nvarchar(10), with a default of NULL. To skip UPDATE STATISTICS, specify true. To explicitly run UPDATE STATISTICS, specify false.

By default, UPDATE STATISTICS is performed to update information about the data in the tables and indexes. Performing UPDATE STATISTICS is useful for databases that are to be moved to read-only media.

[ @keepfulltextindexfile = ] N'keepfulltextindexfile'

Specifies that the full-text index file associated with the database that is being detached isn't dropped during the database detach operation. @keepfulltextindexfile is nvarchar(10), with a default of true.

  • If @keepfulltextindexfile is false, all the full-text index files associated with the database and the metadata of the full-text index are dropped, unless the database is read-only.
  • If NULL or true, full-text related metadata is kept.

Important

This feature will be removed in a future version of SQL Server. Avoid using this feature in new development work, and plan to modify applications that currently use this feature.

Return code values

0 (success) or 1 (failure).

Result set

None.

Remarks

When a database is detached, all its metadata is dropped. If the database was the default database of any login accounts, master becomes their default database.

Note

For information about how to view the default database of all the login accounts, see sp_helplogins. If you've the required permissions, you can use ALTER LOGIN to assign a new default database to a login.

Limitations

A database can't be detached if any of the following are true:

  • The database is currently in use. For more information, see Obtain exclusive access.

  • If replicated, the database is published.

    Before you can detach the database, you must disable publishing by running sp_replicationdboption.

    If you can't use sp_replicationdboption, you can remove replication by running sp_removedbreplication.

  • A database snapshot exists on the database.

    Before you can detach the database, you must drop all of its snapshots. For more information, see Drop a Database Snapshot.

    A database snapshot can't be detached or attached.

  • The database is being mirrored.

    The database can't be detached until the database mirroring session is terminated. For more information, see Removing Database Mirroring (SQL Server).

  • The database is suspect.

    You must put a suspect database into emergency mode before you can detach the database. For more information about how to put a database into emergency mode, see ALTER DATABASE.

  • The database is a system database.

Obtain exclusive access

Detaching a database requires exclusive access to the database. If the database that you want to detach is in use, before you can detach it, set the database to SINGLE_USER mode to obtain exclusive access.

Before you set the database to SINGLE_USER, verify that the AUTO_UPDATE_STATISTICS_ASYNC option is set to OFF. When this option is set to ON, the background thread that is used to update statistics takes a connection against the database, and you're unable to access the database in single-user mode. For more information, see Set a database to single-user mode.

For example, the following ALTER DATABASE statement obtains exclusive access to the AdventureWorks2022 database after all current users disconnect from the database.

USE master;
ALTER DATABASE AdventureWorks2022
SET SINGLE_USER;
GO

To force current users out of the database immediately or within a specified number of seconds, you can also use the ROLLBACK option.

ALTER DATABASE <database_name>
SET SINGLE_USER
WITH ROLLBACK <rollback_option>;

For more information, see ALTER DATABASE.

Reattach a database

The detached files remain and can be reattached by using CREATE DATABASE (with the FOR ATTACH or FOR ATTACH_REBUILD_LOG option). The files can be moved to another server and attached there.

Permissions

Requires membership in the sysadmin fixed server role or membership in the db_owner role of the database.

Examples

The Transact-SQL code samples in this article use the AdventureWorks2022 or AdventureWorksDW2022 sample database, which you can download from the Microsoft SQL Server Samples and Community Projects home page.

The following example detaches the AdventureWorks2022 database with @skipchecks set to true.

EXEC sp_detach_db 'AdventureWorks2022', 'true';

The following example detaches the AdventureWorks2022 database and keeps the full-text index files and the metadata of the full-text index. This command runs UPDATE STATISTICS, which is the default behavior.

EXEC sp_detach_db @dbname = 'AdventureWorks2022',
    @keepfulltextindexfile = 'true';

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