UPDATE одной строки несколько раз - MySQL

UPDATE stock_metal AS s 
    JOIN workpiece AS w ON s.Id = w.Type_metal
    JOIN type_work AS t ON w.Id = t.After_workpiece
    RIGHT JOIN composition AS c ON w.Id = c.Id_workpiece
    SET s.Length = s.Length - w.Size
    WHERE c.Id_type_work = 6;

UPDATE

w.Size

UPDATE