teacher表
select t.t_no,t.t_name,t.t_age from teacher t where t.t_age > any (select t_age from teacher where t_age>29);
>any的意思是大於任意一條即可,所以結果等價於 >30,即只有59的符合條件
select t.t_no,t.t_name,t.t_age from teacher t where t.t_age < all (select t_age from teacher where t_age>29);
<all 的意思是,小於所有的,即小於裏邊最小的那個,即<30