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Student(S#,Sname,Sage,Ssex) ѧÉú±í
Course(C#,Cname,T#) ¿Î³Ì±í
SC(S#,C#,score) ³É¼¨±í
Teacher(T#,Tname) ½Ìʦ±í
ÎÊÌ⣺
1¡¢²éѯ“001”¿Î³Ì±È“002”¿Î³Ì³É¼¨¸ßµÄËùÓÐѧÉúµÄѧºÅ£»
select a.S# from (select s#,score from SC where C#='001') a,(select s#,score
from SC where C#='002') b
where a.score>b.score and a.s#=b.s#;
2¡¢²éѯƽ¾ù³É¼¨´óÓÚ60·ÖµÄͬѧµÄѧºÅºÍƽ¾ù³É¼¨£»
select S#,avg(score)
from sc
group by S# having avg(score) >60;
3¡¢²éѯËùÓÐͬѧµÄѧºÅ¡¢ÐÕÃû¡¢Ñ¡¿ÎÊý¡¢×ܳɼ¨£»
select Student.S#,Student.Sname,count(SC.C#),sum(score)
from Student left Outer join SC on Student.S#=SC.S#
group by Student.S#,Sname
4¡¢²éѯÐÕ“ÀÄÀÏʦµÄ¸öÊý£»
select count(distinct(Tname))
from Teacher
where Tname like 'Àî%';
5¡¢²éѯûѧ¹ý“Ҷƽ”ÀÏʦ¿ÎµÄͬѧµÄѧºÅ¡¢ÐÕÃû£»
select Student.S#,Student.Sname
from Student
where S# not in (select distinct( SC.S#) from SC,Course,Teacher where SC.C#=Course.C# and Teacher.T#=Course.T# and Teacher.Tname='Ҷƽ');
6¡¢²éѯѧ¹ý“001”²¢ÇÒҲѧ¹ý±àºÅ“002”¿Î³ÌµÄͬѧµÄѧºÅ¡¢ÐÕÃû£»
select Student.S#,Student.Sname from Student,SC where Student.S#=SC.S# and SC.C#='001'and exists( Select * from SC as SC_2 where SC_2.S#=SC.S# and SC_2.C#='002');
7¡¢²éѯѧ¹ý“Ҷƽ”ÀÏʦËù½ÌµÄËùÓпεÄͬѧµÄѧºÅ¡¢ÐÕÃû£»
select S#,Sname
from Student
where S# in (select S# from SC ,Course ,Teacher where SC.C#=Course.C# and Teacher.T#=Course.T# and Teacher.Tname='Ҷƽ' group by S# having count(SC.C#)=(select count(C#) from Course,Teacher where Teacher.T#=Course.T# and Tname='Ҷƽ'));
8¡¢²éѯ¿Î³Ì±àºÅ“002”µÄ³É¼¨±È¿Î³Ì±àºÅ“001”¿Î³ÌµÍµÄËùÓÐͬѧµÄѧºÅ¡¢ÐÕÃû£»
Select S#,Sname from (select Student.S#,Student.Sname,score ,(select score from SC SC_2 where SC_2.S#=Student.S# and SC_2.C#='002') score2
from Student,SC where Student.S#=SC.S# and C#='001') S_2 where score2 <score;
9