ACP --> Maintenance --> Execute SQL Query
Make sure your userid is set to be able to run queries via the config file.
Code:
// ****** USERS WITH QUERY RUNNING PERMISSIONS ******
// The users specified here will be allowed to run queries from the control panel.
// See the above entries for more information on the format.
// Please note that the ability to run queries is quite powerful. You may wish
// to remove all user IDs from this list for security reasons.
$config['SpecialUsers']['canrunqueries'] = 'X';