sql面试题目

有3个表S,C,SC

S(SNO,SNAME)代表(学号,姓名)

C(CNO,CNAME,CTEACHER)代表(课号,课名,教师)

SC(SNO,CNO,SCGRADE）代表(学号,课号,成绩)

1 找出没有选过'黎明"老师的所有学生姓名

select s.sname

from sc,s

where sc.cno in ( select distinct cno

from c

where cteacher!='黎明' ) and sc.sno=s.sno

2 列出2门以上不及格学生的姓名和平均成绩

select s.sname,t.avg_grade

from s, select sno,avg(scgrade) avg_grade

from sc

where scgrade<60

group by sno

having count(cno)>=2 ) t

where s.sno=t.sno

3 学过1号课程又学过2号课所有学生的姓名

select s.sname

from sc ,s

where sc.cno='1' and sc.sno in (select distinct sno

from sc

where sc.cno='2' ) and sc.sno=s.sno