select t2.name ,count(examid),count(decode(sign(to_number(grade)-90),-1,null)) from t1.t2 where t1.studentid=t2.studentid(+);
select t2.name ,count(t1.examid), count(decode(sign(to_number(t1.grade)-90),-1,null)) from t1﹐t2 where t1.studentid=t2.studentid(+); 思想就是這樣啦﹐decode函數得方法記得不時很明確﹐自己查查﹐我現在手上沒書。
select b.studentid,b.name,count(a.studentid) 考试的次数,count(decode(sign(to_number(a.grade)-90),1,null)) 优秀的次数 from 表1 a,表2 b where a.studentid(+)=b.studentid group by b.studentid,b.name
from t1.t2
where t1.studentid=t2.studentid(+);
count(decode(sign(to_number(t1.grade)-90),-1,null))
from t1﹐t2
where t1.studentid=t2.studentid(+);
思想就是這樣啦﹐decode函數得方法記得不時很明確﹐自己查查﹐我現在手上沒書。