Error 1054 when select *

[Yuval Cohen]

I create the following stored proc:
====================

DELIMITER $$
DROP procedure IF EXISTS `test` $$
CREATE PROCEDURE `test` (IN num INT)
BEGIN

drop table if exists temp_test;

IF num = 0 THEN
create table temp_test ENGINE=MEMORY as
select
'zero' as zero;
ELSE
create table temp_test ENGINE=MEMORY as
select
'not-zero' as not_zero;
END IF;
SELECT * from temp_test;
drop table temp_test;
END$$

================

Then I try to run:
call test(0);
followed by:
call test(1);

Which output error: Error Code 1054 Unknown column temp_test.zero' in field list.

Strange enough, if I recompile the stored proc, or diconnect => reconnect, and run:
call test(1);
followed by:
call test(0);

The first call succeed whilst the second call fails with error: Error Code 1054 Unknown column temp_test.non_zero' in field

In any case, the second call fails.
WHY???