select sum(decode(b.CNAME,'语文',成绩)) 语文,sum(decode(b.CNAME,'数学',成绩)) 数学 from SC a join COURCE b on a.CID=b.CID where a.SID=20030405 group by a.sid
3. 查询: 学号为20030405的学生,最高分的科目(20分)
select * from (select b.CNAME from SC a join COURCE b on a.CID=b.CID where a.SID=20030405 order by SCORE desc) where rownum=1
4. 查询:语文最高分学生姓名(15分)
select * from (select c.sNAME from SC a join COURCE b on a.CID=b.CID join student c on a.sid=c.sid where b.CNAME='语文' order by SCORE desc) where rownum=1
2、
select sum(decode(科目代号,'1',成绩)),sum(decode(科目代号,'2',成绩)) from
(select 成绩,科目代号 from 关联表 where 学号='20030405' and 科目代号 in (select 科目代号 from 科目表 where 科目名称 in ('语文','数学')))