根据下级状态更新上级状态

原来语句

SET display = 1
WHERE
    id IN (
        SELECT
            a.pid
        FROM
            area a
        WHERE
            a.display = 1
        AND pid != 0
    );

提示：[Err] 1093 – You can’t specify target table ‘area’ for update in FROM clause

修改后

UPDATE area a1,(
        SELECT
            pid
        FROM
            area
        WHERE
            display = 1
        AND pid != 0
    ) a2
SET a1.display = 1
where a1.id=a2.pid;