db_ddladmin
SQL Server 2005
Members of the db_ddladmin fixed database role can run any Data Definition Language (DDL) command in a database.
Reference
Database-Level RolesConcepts
Permissions of Fixed Database RolesOther Resources
sp_dbfixedrolepermission (Transact-SQL)sp_helpdbfixedrole (Transact-SQL)
Security Considerations for Databases and Database Applications