麻烦指导下这个sql语句如何写

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解决时间 2021-05-05 20:44

提问者网友：像風在裏
2021-05-05 01:14

已知关系模式:

S (SNO,SNAME) 学生关系。SNO 为学号，SNAME 为姓名；

C (CNO,CNAME,CTEACHER) 课程关系。CNO 为课程号，CNAME 为课程名，CTEACHER 为任课教师；

SC(SNO,CNO,SCGRADE) 选课关系。SCGRADE 为成绩

请用SQL语句列出有二门以上(含两门)不及格课程的学生姓名及其平均成绩

最佳答案

五星知识达人网友：夜余生
2021-05-05 02:35

条件不完整。。。表的关系没建好。。

全部回答

1楼网友：往事埋风中
2021-05-05 05:40

SELECt S.SNO,S.SNAME,AVG_SCGRADE=AVG(SC.SCGRADE) FROM S,SC,( SELECt SNO FROM SC WHERe SCGRADE<60 GROUP BY SNO HAVINg COUNT(DISTINCT CNO)>=2 )A WHERe S.SNO=A.SNO AND SC.SNO=A.SNO GROUP BY S.SNO,S.SNAME

2楼网友：迟山
2021-05-05 04:57

select s.sno,sname,avg(scgrade) as '平均成绩' from s,sc where s.sno=sc.sno and s.sno in ( select sno from sc where scgrade<'60' group by sno having count(sno)>2 or count(sno)=2 ) group by sname,s.sno

3楼网友：神也偏爱
2021-05-05 03:24

select sname,agv(SCGRADE) from sc inner join s on sc.sno=s.sno inner join c on sc.cno=c.cno group by sname having sc.grade <60 and count(cno)>=2

4楼网友：执傲
2021-05-05 03:05

哈哈终于找到个我可以发挥的题目老

select sname,grade,count(cno） from s,c,sc

group by sname,grade sno s.sno=sc.sno and sc.cno=c.cno

having sno s.sno=sc.sno and sc.cno=c.cno and sc.grade <60 and count(cno)>=2

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