数据库中查询所有参与了考试的学生的考生姓名，年龄，平均成绩，考试次数。

SQL语句如下： select student.sno 学号,sname 姓名,sgrade 入学成绩,count(cno)选课门数,avg(grade)平均分 from student,score where student.sno=score.sno group by student.sno,sname,sgrade其中sno、sname、sgrade、cno、grade分别为：学...

select sname from student

where sno in(

select a.sno from studentcourse a join course b

on a.cno=b.cno

where b.cname='数据库原理' and a.score>90)

select a.sclass as 班级,count(*) as 不及格人数 from

student a join studentcourse b

on a.sno=b.sno

where b.score<60

group by a.sclass

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