Logging trigger activity and RAISE error

[David Harbeson]

I've got a trigger that enforces business rules (I can't use a foreign key in this case), and I want it to log the fact that it fired. I have two stored procedures that: 1-insert to a log file and 2-raise an error. No matter what I've tried, I cannot get it to insert to the log file. It seems that the raise does some form of rollback.

Is there any work around for this?
========
CREATE TRIGGER bd_department_fer BEFORE DELETE ON department
FOR EACH ROW
BEGIN
DECLARE error_name VARCHAR(64) DEFAULT 'bd_department_fer';
DECLARE error_field VARCHAR(256) DEFAULT '';
DECLARE error_text VARCHAR(1024) DEFAULT '';
DECLARE check_count INT;

SET error_field=CONCAT('department_id=',OLD.department_id);


SET check_count=(SELECT COUNT(*) FROM hierarchy_node hn WHERE hn.child_id=OLD.department_id AND hn.child_type=4);
IF (check_count > 0) THEN
SET error_text='Cannot delete deparment record because it exists in the
hierarchy_node table';

CALL usp_insertTriggerLog(error_name,error_field,error_text);
CALL usp_raiseException(error_text);
END IF;

END; $$
========
DROP PROCEDURE IF EXISTS `usp_insertTriggerLog`; $$
CREATE PROCEDURE `usp_insertTriggerLog`(IN _name VARCHAR(64), IN _field VARCHAR(256), IN _text VARCHAR(1024) )
SQL SECURITY INVOKER
BEGIN
INSERT INTO trigger_log (`trigger_name`, `trigger_field`, `trigger_error_text`) VALUES (_name,_field,_text);
END $$
========
DROP PROCEDURE IF EXISTS `usp_raiseException`; $$
CREATE PROCEDURE `usp_raiseException`(IN _text VARCHAR(1024) )
SQL SECURITY INVOKER
BEGIN
DECLARE generic_error CONDITION FOR SQLSTATE '45000';

SIGNAL generic_error
SET MESSAGE_TEXT=_text;
END $$