mysql存储过程从表取数据存储到游标然后批量修改

delimiter $create PROCEDURE category()BEGIN    DECLARE  categoryName varchar(50);        DECLARE  parentId  bigint(20);  DECLARE  itemId  bigint(20);      -- 遍历数据结束标志    DECLARE done INT DEFAULT FALSE;    -- 游标    DECLARE cur_account CURSOR FOR SELECT a.id,b.name,b.parent_id FROM tb_item a, tb_item_cat b where a.cid = b.id;    -- 将结束标志绑定到游标    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;        -- 打开游标    OPEN  cur_account;         -- 遍历    read_loop: LOOP            -- 取值 取多个字段            FETCH  NEXT from cur_account INTO itemId,categoryName,parentId;            IF done THEN                LEAVE read_loop;             END IF;         -- 你自己想做的操作        update tb_item set name = categoryName,parent_id = parentId where id = itemId;    END LOOP;      CLOSE cur_account;END $