Result consisted of more than one row Error 1172 mysql

Question

Hello im having a hard time with this stored procedure. im getting the error: Result consisted of more than one row.

here is my stored procedure:

DELIMITER $$

DROP PROCEDURE IF EXISTS `dss`.`COSTRET` $$
CREATE DEFINER=`dwadmin`@`192.168.%.%` PROCEDURE `COSTRET`( TDATE DATE)
BEGIN
    DECLARE done INT DEFAULT 0;
    DECLARE ls_id VARCHAR(8);
    DECLARE ld_cost DECIMAL(10,4);
      DECLARE ld_retail DECIMAL(10,4);
    DECLARE cur1 CURSOR FOR SELECT DISTINCT `id` FROM `prod_performance` WHERE `psc_week` = TDATE;
    DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done = 1;

  -- Get the Cost
  CREATE TEMPORARY TABLE IF NOT EXISTS `prod_itemcost`
    SELECT DISTINCTROW `itemcode` ID, `mlist` COST
    FROM (SELECT `itemcode`, `pceffdate`, `mlist`
        FROM `purchcost` a
        where `pceffdate` = (SELECT MAX(z.`pceffdate`) FROM `purchcost` z WHERE z.`itemcode` = a.`itemcode`
        AND z.`pceffdate` <= TDATE)) tb
    ORDER BY `itemcode`;

    OPEN cur1;
    REPEAT
      FETCH cur1 INTO ls_id;
      IF NOT done THEN
            SELECT DISTINCTROW `cost` INTO ld_cost FROM `prod_itemcost` WHERE id = ls_id;

        UPDATE LOW_PRIORITY `prod_performance` SET `current_cost` = ld_cost WHERE `psc_week` = TDATE and `id` = ls_id;
      END IF;
    UNTIL done END REPEAT;
    CLOSE cur1;

   -- Destroy Temporary Tables
   DROP TEMPORARY TABLES IF EXISTS `prod_itemcost`;
END $$

DELIMITER ;

Any solutions and recommendations are much appreciated!

Answer 1

This line

SELECT MAX(z.`pceffdate`) FROM `purchcost` z WHERE z.`itemcode` = a.`itemcode`
    AND z.`pceffdate` <= TDATE

has got to be the problem. It must be returning more than 1 row. So, the DBMS is trying to set multiple values to the same thing, which of course it cannot do.

Do you need something else in your WHERE clause there?