Syntax:
DROP {DATABASE | SCHEMA} [IF EXISTS] db_name

DROP DATABASE drops all tables in the database and deletes the
database. Be very careful with this statement! To use DROP DATABASE,
you need the DROP privilege on the database. DROP SCHEMA is a synonym
for DROP DATABASE.

*Important*: When a database is dropped, user privileges on the
database are not automatically dropped. See [HELP GRANT].

IF EXISTS is used to prevent an error from occurring if the database
does not exist.

URL: http://dev.mysql.com/doc/refman/5.1/en/drop-database.html

