Mysql procedure: nesting begin statements in conditional blocks - mysql

Question

I am trying to only execute a block of code if a variable exists. Here is a code snipit. Can you nest Begin...End statements in an IF block?
I've re-designed this several times. Suggestions?
delimiter //
drop trigger if exists example_trigger;//
create trigger example_trigger AFTER UPDATE on some_table for each row
BLOCK1: begin
-- check current status
DECLARE done BOOLEAN DEFAULT FALSE;
-- cap check
if (new.CURRENT_ALLOCATED >= new.TOTAL_ALLOWED_QTY) then
SET done = TRUE;
end if; -- cap check end
-- o
if (done != TRUE and new.O_KEY is not null and new.A_KEY is null) then
OBLOCK: begin
DECLARE done_o BOOLEAN DEFAULT FALSE;
DECLARE pd_nbr INT;
DECLARE no_more_rows BOOLEAN;
DECLARE cur_pd CURSOR FOR
select pd.STATUS_KEY
from PROD_DEL_V pd
join PROD_T p on pd.KEY_NBR = p.KEY_NBR
where pd.STATUS not in ('PU', 'EX')
and p.O_KEY = new.O_KEY;
DECLARE CONTINUE HANDLER FOR NOT FOUND
SET done_o = TRUE;
-- run updates
if (done_o != TRUE) then
-- open cursor
OPEN cur_pd;
-- loop start
loop_it: LOOP
FETCH cur_pd INTO pd_nbr;
-- exit loop if..
if no_more_rows = TRUE THEN
CLOSE cur_pd;
LEAVE loop_it;
end if;
INSERT INTO STATUS_TABLE (
STATUS_KEY
, STATUS
, NOTE_TXT
)
(
SELECT
PD.STATUS_KEY
, 'PU' AS STATUS
, concat('example_trigger - MAX has been reached or exceeded [TOTAL_ALLOWED_QTY = ',new.TOTAL_ALLOWED_QTY,' and CURRENT_ALLOCATED = ', new.CURRENT_ALLOCATED, ']') AS NOTE_TXT
FROM PROD_DEL_TABLE PD
WHERE PD.STATUS_KEY = pd_nbr
);
END LOOP loop_it;
end if; -- run updates end
end OBLOCK:; -- end block
end if; -- o
-- a
if (done != TRUE and new.O_KEY is null and new.A_KEY is not null) then
ABLOCK: begin
DECLARE done_a BOOLEAN DEFAULT FALSE;
DECLARE pd_nbr INT;
DECLARE no_more_rows BOOLEAN;
DECLARE cur_pd CURSOR FOR
select pd.STATUS_KEY
from PROD_DEL_V pd
join PROD_T p on pd.KEY_NBR = p.KEY_NBR
join A_O_T a on a.O_KEY = p.O_KEY
where pd.STATUS not in ('PU', 'EX')
and a.A_KEY = new.A_KEY;
DECLARE CONTINUE HANDLER FOR NOT FOUND
SET done_a = TRUE;
-- run updates
if (done_a != TRUE) then
-- open cursor
OPEN cur_pd;
-- loop start
loop_it: LOOP
FETCH cur_pd INTO pd_nbr;
-- exit loop if..
if no_more_rows = TRUE THEN
CLOSE cur_pd;
LEAVE loop_it;
end if;
INSERT INTO STATUS_TABLE (
STATUS_KEY
, STATUS
, NOTE_TXT
)
(
SELECT
PD.STATUS_KEY
, 'PU' AS STATUS
, concat('example_trigger - MAX has been reached or exceeded [TOTAL_ALLOWED_QTY = ',new.TOTAL_ALLOWED_QTY,' and CURRENT_ALLOCATED = ', new.CURRENT_ALLOCATED, ']' AS NOTE_TXT
FROM PROD_DEL_TABLE PD
WHERE PD.STATUS_KEY = pd_nbr
);
END LOOP loop_it;
end if; -- run updates end
end ABLOCK; -- end block
end if; -- a
end BLOCK1; -- end large block
//
delimiter ;

Answer 1

What is the problem with IF and BEGIN...END clause? Take a look at this simple example -
CREATE PROCEDURE procedure1(IN Param1 VARCHAR(255))
BEGIN
IF Param1 = 1 THEN
BEGIN
DECLARE i INT;
-- do something
END;
ELSE
BEGIN
DECLARE i INT;
-- do something
END;
END IF;
END