Cacher is the code snippet organizer for pro developers

// to show the error message with 500 error
$db['default'] = array(
	'db_debug' => (ENVIRONMENT !== 'production'),
);

// to catch the error messages in the php model failure condition.

$db['default'] = array(
	'db_debug' => FALSE,
);

----------------------
// keep this code in the else condition and this code will return the database error.

 $error = $this->db->error();
                    $this->db->trans_rollback();
                    return $error;

------------------------
//Inside the model
// executed query.
 $b_query = $this->db->insert('project_mn', $data);
 
 // if any errors then it will display the error message.
 if(!@$this->db->query($b_query))
                {
                    $error = $this->db->error();
                    return $error;
                    // do something in error case
                }else{
                    return "Success";
                    // do something in success case
                }