Question

I’ve been battling with this for too long so I’m here to ask for help…

I have a MySQL stored procedure that I want to do the following:

given an ‘id’ and a ‘username’ for a given record

1. if id does not exist in table then create record
2. else if id exists and username is not the same as what exists then update record
3. else do nothing

I’ve tried the following:

BEGIN

DECLARE doCreate INT;
DECLARE doUpdate INT;
SELECT COUNT(*) INTO doCreate FROM app_user WHERE id=1;
IF (doCreate > 0) THEN 
   SELECT COUNT(*) INTO doUpdate FROM app_user WHERE id=1 AND username='other';
END IF

IF(doCreate = 0) THEN ---SYNTAX ERROR ON THIS LINE---
   SELECT 'CREATE';
ELSE IF(doUpdate = 0) THEN
   SELECT 'UPDATE';
ELSE
   SELECT 'NOTHING';
END IF

END

I’ve also tried replacing the if-elseif-else block with a case statement but get the same result…

CASE ---ERROR ON THIS LINE---
   WHEN doCreate = 0 THEN 
      SELECT 'CREATE';
   WHEN doUpdate = 0 THEN
      SELECT 'UPDATE';
   ELSE
      SELECT 'NOTHING';
END

• I seem to get a syntax error on anything that comes after the first END IF, so that’s the first problem that occurs…

Any help would be appreciated – I’m sure there’s a better way to do this.

Answer 1

I believe you’ll need to terminate the END IFs with ;, and internally ELSEIF should be one word. Otherwise, another END IF is needed, but not found.

IF (doCreate > 0) THEN 
   SELECT COUNT(*) INTO doUpdate FROM app_user WHERE id=1 AND username='other';
END IF; /* terminate with ; */

IF(doCreate = 0) THEN 
   SELECT 'CREATE';
ELSEIF(doUpdate = 0) THEN
   SELECT 'UPDATE';
ELSE
   SELECT 'NOTHING';
END IF; /* terminate with ; */

Look over the MySQL IF/ELSE syntax reference for various usage examples.