ALTER DATABASE [db_name]
    alter_specification ...

alter_specification:
    [DEFAULT] CHARACTER SET [=] charset_name
  | [DEFAULT] COLLATE [=] collation_name

ALTER DATABASE enables you to change the overall characteristics of a database. These characteristics are stored in the db.opt file in the database directory. To use ALTER DATABASE, you need the ALTER privilege on the database.

The CHARACTER SET clause changes the default database character set. The COLLATE clause changes the default database collation. Section 9.1, “Character Set Support”, discusses character set and collation names.

Beginning with MySQL 4.1.0, you can see what character sets and collations are available using, respectively, the SHOW CHARACTER SET and SHOW COLLATION statements. See Section 12.4.5.3, “SHOW CHARACTER SET Syntax”, and Section 12.4.5.4, “SHOW COLLATION Syntax”, for more information.

ALTER DATABASE was added in MySQL 4.1.1. Beginning with MySQL 4.1.8, the database name can be omitted, in which case the statement applies to the default database.

MySQL Enterprise.  In a production environment, alteration of a database is not a common occurrence and may indicate a security breach. Advisors provided as part of the MySQL Enterprise Monitor automatically alert you when data definition statements are issued. For more information, see http://www.mysql.com/products/enterprise/advisors.html.