MySQL delete 取别名 delete alias_name from table_name {where cause}

-- 错误写法
delete from tab_name t1 where t1.col_name = val;
-- 小例子
DELETE
FROM
    priv_user_role pur
WHERE
    EXISTS (
        SELECT
            pr.id
        FROM
            priv_role pr
        WHERE
            pr.platform_id = 2
        AND pur.role_id = pr.id
    )
  -- 运行报错：
  WHERE
    EXISTS (
        SELECT
            pr.id
        FROM
            priv_role pr
        WHERE
            pr.platform_id = 2
        AND pur.role_id = pr.id
    )
[Err] 1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'pur
WHERE
    EXISTS (
        SELECT
            pr.id
        FROM
            priv_role pr
        WHERE
            ' at line 3
-- delete 是可以取别名的，准确写法
delete a from table1 a where a.status=2
and EXISTS (select b.id from table2 b where b.fid=a.id)