Codeigniter中禁止A Database Error Occurred错误提示的方

define('ENVIRONMENT', 'production'); //默认是development
if (defined('ENVIRONMENT')) 
{ 
    switch (ENVIRONMENT) 
    { 
        case 'development': 
            error_reporting(E_ALL); 
        break; 

        case 'testing': 
        case 'production': 
            error_reporting(0); 
        break; 

        default: 
            exit('The application environment is not set correctly.'); 
    } 
}

$db['default']['db_debug'] = FALSE;