key1:
SELECT a.sid from (select sid from tb_stu where 1=1 ORDER BY id DESC) a INNER join tb_award b on a.sid+0=b.stu_sid+0key2:
SELECT sid FROM tb_stu A where exists (select stu_sid as sid from tb_award B where B.stu_sid+0 = A.sid+0 group by B.id) ORDER BY A.id;这是现在的方案一和方案二，但是实在太慢了。
希望大佬可以提个优化建议。
