简化MySQL子查询

Question

如何简化此MySQL子查询？

Select * From tbl_sys_usuarios Where usr_CvePA IN 
(Select sub_usrCveDep From tbl_sys_usuarios_subalternos Where sub_usrCvePA IN (Select sub_usrCveDep From tbl_sys_usuarios_subalternos Where sub_usrCvePA='237')) 

Answer 1

如果你想摆脱嵌套查询的，这应该工作：

SELECT tsu.* 
FROM tbl_sys_usarios tsu 
INNER JOIN tbl_sys_usarios_subalternos tsus_a ON tsu.usr_CvePA = tsus.sub_usrCveDep 
INNER JOIN tbl_sys.tbl_sys_usarios_subalternos tsus_b ON tsus_a.sub_usrCvePA = tsus_b.sub_usrCveDep 
WHERE tsus_b.sub_usrCvePA = '237' 

Answer 2

这就是答案！我这么...

Select * From tbl_sys_usuarios u 
Join tbl_sys_usuarios_subalternos sub1 ON u.usr_CvePA=sub1.sub_UsrCveDep 
Join tbl_sys_usuarios_subalternos sub2 ON sub1.sub_UsrCvePA=sub2.sub_UsrCveDep and sub2.sub_UsrCvePA='237' 

谢谢！