==============================================================
create table test2_04 as
(select distinct S.SID,S.NAME
from pub.COURSE C,pub.STUDENT_COURSE SC,pub.STUDENT S
where C.NAME='操作系统' and s.SID=sc.sid and c.CID=sc.cid)
intersect(
select distinct S.SID,S.NAME
from pub.COURSE C,pub.STUDENT_COURSE SC,pub.STUDENT S
where C.NAME='数据结构'and s.SID=sc.sid and c.CID=sc.cid)
============================================================
create table test2_05 as
select SC.SID, s.NAME, round(avg(sc.SCORE),0) avg_score,sum(sc.SCORE) sum_score
from pub.STUDENT S,pub.STUDENT_COURSE SC
where s.SID=SC.sid and s.AGE=20
group by SC.SID, s.NAME
=============================================================
update dbtest set test=2
select* from dbscore
=============================================================
create table test2_10 as
select s.SID,s.NAME
from pub.STUDENT_COURSE SC, pub.STUDENT S
where s.SID=sc.sid and sc.SCORE<60
group by s.SID,s.NAME,sc.CID
having count(*)>=2
===========================================================
create table test2_08 as
select substr(s.NAME,1,1) second_name,count(*) p_count
from pub.STUDENT S
group by substr(s.NAME,1,1)
=============================================================
create table test2_06 as
select cid,max(score) max_score
from pub.STUDENT_COURSE SC
group by cid
===============================================================
delete from test3_03
where sid not in
((select sid
from test3_03
where sex in('男'，'女')and sex like '_')--一个字符
union
(select sid
from test3_03
where sex is null))
===============================================================
NOT LIKE '%[^0-9]%
=========================
delete from test3_04
where sid in(
(select sid
from test3_04
where dname like '% %')--挑选出含空格的
