mysql error handling with signal/resignal - mysql

Question

I would like to have a check for valid load types. If a load type passed into my procedure is invalid, I want to throw an error message via SIGNAL. I also want to have a generic EXIT handler for any other unexpected errors which will rollback any changes. The problem is the generic EXIT handler is taking precedence over my custom SIGNAL and all I get is 'SQLException encountered'. Unless i remove the generic EXIT handler, in which case I get 'Load type is incorrect'.
code:
DECLARE incorrect_load_type CONDITION FOR SQLSTATE '22012';
DECLARE EXIT HANDLER FOR incorrect_load_type
RESIGNAL SET MESSAGE_TEXT = 'Load type is incorrect';
DECLARE EXIT HANDLER FOR SQLEXCEPTION, SQLWARNING
begin
SELECT 'SQLException encountered';
rollback;
end;
IF(v_load_type != 'CORRECT TYPE') THEN
SIGNAL incorrect_load_type;
END IF;

Answer 1

Try this
DECLARE incorrect_load_type CONDITION FOR SQLSTATE '22012';
DECLARE EXIT HANDLER FOR incorrect_load_type
begin
SELECT 'Load type is incorrect';
end;
DECLARE EXIT HANDLER FOR SQLEXCEPTION, SQLWARNING
begin
SELECT 'SQLException encountered';
rollback;
end;
IF (v_load_type != 'CORRECT TYPE') THEN
SIGNAL incorrect_load_type;
END IF;

Answer 2

What I would do is this:
DECLARE custom_exception CONDITION FOR SQLSTATE '45000';
DECLARE EXIT HANDLER FOR SQLEXCEPTION begin
rollback;
resignal;
end;
IF v_load_type != 'CORRECT TYPE' THEN
SIGNAL custom_exception set message_text = 'Load type is incorrect';
END IF;
Notice that I've created a generic custom exception, and set the message text when it is signaled. This allows the generic SQLEXCEPTION exit handler to catch it and propagate that error message.
Next, I have deleted the handler for the custom exception.
Lastly, I have removed SQLWARNING from the exit handler. This is to avoid catching harmless warnings that ends up aborting the execution (since the "exit" handler would have caught it had SQLWARNING been included) but would yet totally mask out the reason (likely bcoz warnings aren't signaled, I'm guessing. And hence, despite the "resignal", there is nothing to resignal, so nothing is resignaled! And what ends up happening is: A warning (eg. data truncation) is caught and execution aborted, with no indication of this having happened!)
This is what I seem to be seeing from my experience.
Coming from an Oracle background, I can positively state that exception handling in MySQL grossly sucks!