MySQL: IF / THEN statements in stored procedures - mysql

Question

I'm writing a stored procedure that uses multiple IF / THEN statements that also need to execute multiple queries if they evaluate to true. Problem is, I can't seem to find any examples of the appropriate syntax. From the MySQL dev handbook, it seems like I could have multiple queries in the "statement_list," but so far I can't get it to work.
Here's what I'm trying to do:
SET agency =
COALESCE((SELECT org_agency_o_id
FROM orgs_agencies
WHERE org_agency_code = maj_agency_cat)
,(SELECT min(org_id)
FROM orgs
WHERE org_name LIKE CONCAT('U.S.',SUBSTRING(maj_agency_cat,5))))
IF agency IS NULL THEN
-- execute multiple queries
INSERT INTO orgs (org_name
,org_name_length
,org_type
,org_sub_types)
VALUES (CONCAT('U.S. ',SUBSTRING(maj_agency_cat,5))
,LENGTH(CONCAT('U.S. ',SUBSTRING(maj_agency_cat,5)))
,'org','Org,GovernmentEntity,Federal,Agency');
SET agency = LAST_INSERT_ID();
END IF;
The error:
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'IF agency IS NULL THEN
INSERT INTO orgs (org_name,org_name_length,org_type,' at line 53
Any ideas? I know it has to be something simple, so I would greatly appreciate anybody's input.

Answer 1

You got a few issues as far as I can see:
As David pointed out, each and every statement needs to be terminated by a ;
If you do a SELECT, better make sure it can only select one value by doing a LIMIT 1; If you've got an aggregate function like min() then only one value can come out.
If you writing the procedure using the CREATE PROCEDURE ... syntax, don't forget to set DELIMITER $$ before the CREATE PROCEDURE ... END $$ body and a DELIMITER ; after.
If you have multiple statements inside your IF THEN ... END IF block, it's a good idea to put them inside a BEGIN ... END; block.
If you have a return value, like agency here, why not make it a FUNCTION name (arg1: INTEGER) RETURNS INTEGER instead of a PROCEDURE name (IN arg1 INTEGER, OUT agency INTEGER). The function is much more versatile.
DELIMITER $$
CREATE PROCEDURE name(arg1 INTEGER, arg2 INTEGER, ...)
BEGIN
SELECT SET agency =
COALESCE((SELECT org_agency_o_id
FROM orgs_agencies
WHERE org_agency_code = maj_agency_cat) LIMIT 1,
(SELECT min(org_id) FROM orgs
WHERE org_name LIKE CONCAT('U.S.',SUBSTRING(maj_agency_cat,5))));
IF agency IS NULL THEN BEGIN
-- execute multiple queries
INSERT INTO orgs (org_name
,org_name_length
,org_type
,org_sub_types)
VALUES (CONCAT('U.S. ',SUBSTRING(maj_agency_cat,5))
,LENGTH(CONCAT('U.S. ',SUBSTRING(maj_agency_cat,5)))
,'org','Org,GovernmentEntity,Federal,Agency');
SET agency = LAST_INSERT_ID();
END; END IF;
END $$
DELIMITER ;

Answer 2

No semicolon after your first SET statement.