MySQL, процедуры и warning 1329

[Vinolentus]

Исходная таблица.

CREATE TABLE `character_zones`
(
    `guid`  INT(11)     UNSIGNED NOT NULL DEFAULT '0',
    `idx`   TINYINT(3)  UNSIGNED NOT NULL DEFAULT '0',
    `val`   INT(11)     UNSIGNED NOT NULL DEFAULT '0',

    PRIMARY KEY (`guid`, `idx`)
) ENGINE = InnoDB;

Процедура.

DELIMITER $$
CREATE PROCEDURE `ConvertZones`() DETERMINISTIC
BEGIN
    DECLARE char_guid   INT(11);
    DECLARE in_str      TEXT;
    DECLARE out_idx     INT;
    DECLARE out_val     INT;
    DECLARE next_row    INT;
    DECLARE res CURSOR FOR SELECT `guid`, `exploredZones` FROM `characters`;
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET next_row = 0;

    SET next_row = 1;
    OPEN res;
    WHILE next_row != 0 DO
        FETCH res INTO char_guid, in_str;
        IF next_row != 0 THEN
            SET out_idx = 0;
            WHILE in_str != '' DO
                SET out_val = CAST(SUBSTRING_INDEX(in_str, ' ', 1) AS UNSIGNED INTEGER);
                SET in_str = SUBSTRING(in_str, 1 + 1 + CHAR_LENGTH(out_val));
                IF (out_val != 0) THEN
                    INSERT INTO `character_zones` (`guid`, `idx`, `val`)
                    VALUES (char_guid, out_idx, out_val);
                END IF;
                SET out_idx = out_idx + 1;
            END WHILE;
        END IF;
    END WHILE;
    CLOSE res;
END$$
DELIMITER ;

Вызываю

CALL ConvertZones();

, вроде отрабатывает корректно, таблицу заполняет, но выдает

0 row(s) affected, 1 warning(s):
1329 No data - zero rows fetched, selected, or processed

В чем подвох, что я делаю не так?

возможно

SELECT count(*) from characters WHERE exploredZones IS NULL