ALTER DATABASE (Transact-SQL)

مقالة
08/06/2013

Modifies a database, or the files and filegroups associated with the database. Adds or removes files and filegroups from a database, changes the attributes of a database or its files and filegroups, changes the database collation, and sets database options. Database snapshots cannot be modified. To modify database options associated with replication, use sp_replicationdboption.

Because of its length, the ALTER DATABASE syntax is separated into the following topics:

ALTER DATABASE
The current topic provides the syntax for changing the name and the collation of a database.
ALTER DATABASE File and Filegroup Options
Provides the syntax for adding and removing files and filegroups from a database, and for changing the attributes of the files and filegroups.
ALTER DATABASE SET Options
Provides the syntax for changing the attributes of a database by using the SET options of ALTER DATABASE.
ALTER DATABASE Database Mirroring
Provides the syntax for the SET options of ALTER DATABASE that are related to database mirroring.
ALTER DATABASE SET HADR
Provides the syntax for the AlwaysOn Availability Groups options of ALTER DATABASE for configuring a secondary database on a secondary replica of an AlwaysOn availability group.
ALTER DATABASE Compatibility Level
Provides the syntax for the SET options of ALTER DATABASE that are related to database compatibility levels.

Topic link icon Transact-SQL Syntax Conventions

Syntax

ALTER DATABASE { database_name  | CURRENT }
{
    MODIFY NAME = new_database_name 
  | COLLATE collation_name
  | <file_and_filegroup_options>
  | <set_database_options>
}
[;]

<file_and_filegroup_options >::=
  <add_or_modify_files>::=
  <filespec>::= 
  <add_or_modify_filegroups>::=
  <filegroup_updatability_option>::= 

<set_database_options>::=
  <optionspec>::= 
  <auto_option> ::= 
  <change_tracking_option> ::=
  <cursor_option> ::= 
  <database_mirroring_option> ::= 
  <date_correlation_optimization_option> ::=
  <db_encryption_option> ::=
  <db_state_option> ::=
  <db_update_option> ::=
  <db_user_access_option> ::=
  <external_access_option> ::=
  <FILESTREAM_options> ::=
  <HADR_options> ::=  
  <parameterization_option> ::=
  <recovery_option> ::= 
  <service_broker_option> ::=
  <snapshot_option> ::=
  <sql_option> ::= 
  <termination> ::=

Arguments

database_name
Is the name of the database to be modified.

Note

This option is not available in a Contained Database.
CURRENT
Designates that the current database in use should be altered.
MODIFY NAME **=**new_database_name
Renames the database with the name specified as new_database_name.
COLLATE collation_name
Specifies the collation for the database. collation_name can be either a Windows collation name or a SQL collation name. If not specified, the database is assigned the collation of the instance of SQL Server.

For more information about the Windows and SQL collation names, see COLLATE (Transact-SQL).

<file_and_filegroup_options >::=

For more information, see ALTER DATABASE File and Filegroup Options (Transact-SQL).

<set_database_options >::=

For more information, see ALTER DATABASE SET Options (Transact-SQL), ALTER DATABASE Database Mirroring (Transact-SQL), ALTER DATABASE SET HADR (Transact-SQL), and ALTER DATABASE Compatibility Level (Transact-SQL).

Remarks

To remove a database, use DROP DATABASE.

To decrease the size of a database, use DBCC SHRINKDATABASE.

The ALTER DATABASE statement must run in autocommit mode (the default transaction management mode) and is not allowed in an explicit or implicit transaction.

In SQL Server 2005 or later, the state of a database file (for example, online or offline), is maintained independently from the state of the database. For more information, see File States. The state of the files within a filegroup determines the availability of the whole filegroup. For a filegroup to be available, all files within the filegroup must be online. If a filegroup is offline, any try to access the filegroup by an SQL statement will fail with an error. When you build query plans for SELECT statements, the query optimizer avoids nonclustered indexes and indexed views that reside in offline filegroups. This enables these statements to succeed. However, if the offline filegroup contains the heap or clustered index of the target table, the SELECT statements fail. Additionally, any INSERT, UPDATE, or DELETE statement that modifies a table with any index in an offline filegroup will fail.

When a database is in the RESTORING state, most ALTER DATABASE statements will fail. The exception is setting database mirroring options. A database may be in the RESTORING state during an active restore operation or when a restore operation of a database or log file fails because of a corrupted backup file.

The plan cache for the instance of SQL Server is cleared by setting one of the following options:

OFFLINE	READ_WRITE
ONLINE	MODIFY FILEGROUP DEFAULT
MODIFY_NAME	MODIFY FILEGROUP READ_WRITE
COLLATE	MODIFY FILEGROUP READ_ONLY
READ_ONLY	PAGE_VERIFY

Clearing the plan cache causes a recompilation of all subsequent execution plans and can cause a sudden, temporary decrease in query performance. For each cleared cachestore in the plan cache, the SQL Server error log contains the following informational message: "SQL Server has encountered %d occurrence(s) of cachestore flush for the '%s' cachestore (part of plan cache) due to some database maintenance or reconfigure operations". This message is logged every five minutes as long as the cache is flushed within that time interval.

The procedure cache is also flushed in the following scenarios:

A database has the AUTO_CLOSE database option set to ON. When no user connection references or uses the database, the background task tries to close and shut down the database automatically.
You run several queries against a database that has default options. Then, the database is dropped.
A database snapshot for a source database is dropped.
You successfully rebuild the transaction log for a database.
You restore a database backup.
You detach a database.

Changing the Database Collation

Before you apply a different collation to a database, make sure that the following conditions are in place:

You are the only one currently using the database.
No schema-bound object depends on the collation of the database.

If the following objects, which depend on the database collation, exist in the database, the ALTER DATABASEdatabase_nameCOLLATE statement will fail. SQL Server will return an error message for each object blocking the ALTER action:
- User-defined functions and views created with SCHEMABINDING.
- Computed columns.
- CHECK constraints.
- Table-valued functions that return tables with character columns with collations inherited from the default database collation.
Dependency information for non-schema-bound entities is automatically updated when the database collation is changed.

Changing the database collation does not create duplicates among any system names for the database objects. If duplicate names result from the changed collation, the following namespaces may cause the failure of a database collation change:

Object names such as a procedure, table, trigger, or view.
Schema names
Principals such as a group, role, or user.
Scalar-type names such as system and user-defined types.
Full-text catalog names.
Column or parameter names within an object.
Index names within a table.

Duplicate names resulting from the new collation will cause the change action to fail, and SQL Server will return an error message specifying the namespace where the duplicate was found.

Viewing Database Information

You can use catalog views, system functions, and system stored procedures to return information about databases, files, and filegroups.

Permissions

Requires ALTER permission on the database.

Examples

A. Changing the name of a database

The following example changes the name of the AdventureWorks2012 database to Northwind.

USE master;
GO
ALTER DATABASE AdventureWorks2012
Modify Name = Northwind ;
GO

B. Changing the collation of a database

The following example creates a database named testdb with the SQL_Latin1_General_CP1_CI_AS collation, and then changes the collation of the testdb database to COLLATE French_CI_AI.

USE master;
GO

CREATE DATABASE testdb
COLLATE SQL_Latin1_General_CP1_CI_AS ;
GO

ALTER DATABASE testDB
COLLATE French_CI_AI ;
GO

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