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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#,Stud
    
     
	
	
    
    
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