mysql 子查父

--子查父

SELECT T2.*

FROM (

    SELECT

        @r AS _mod_code,

        (SELECT @r := PAR_CODE FROM sys_module WHERE mod_code = _mod_code) AS PAR_CODE,

        @l := @l + 1 AS lvl

    FROM

        (SELECT @r := 502000, @l := 0) vars,

        sys_module h

    WHERE @r <> 0) T1

JOIN sys_module T2

ON T1._mod_code = T2.mod_code

ORDER BY T1.lvl DESC