Обновление одного товара (проверка):
UPDATE shop_items
SET
marking = CONCAT( SUBSTR(marking,2), SUBSTR(marking,1,1) )
WHERE shop_id = YYY
AND shortcut_id = 0
AND modification_id = 0
AND id = NNN;
Обновление всех товаров:
UPDATE shop_items
SET
marking = CONCAT( SUBSTR(marking,2), SUBSTR(marking,1,1) )
WHERE shop_id = YYY
AND shortcut_id = 0
AND modification_id = 0;