数据库练习2(基于数据库练习1)
1.查询“计算机导论”课程比“操作系统”课程成绩高的所有学生的学号;
SELECT sno,degree FROM score WHERE cno =(SELECT cno FROM course WHERE cname ='计算机导论' )
AND degree > ALL(SELECT degree FROM score WHERE cno=(SELECT cno FROM course WHERE cname ='操作系统') GROUP BY degree )
2、查询所有同学的学号、姓名、选课数、总成绩；
SELECT student.sno ,student.sname,COUNT(score.cno),SUM(score.degree) FROM
score LEFT JOIN student ON student.sno=score.sno
GROUP BY score.sno LIMIT 5;
3、查询没学过“刘冰”老师课的同学的学号、姓名；
SELECT t3.sno,t3.sname FROM student t3 ,score t4
WHERE t3.sno=t4.sno AND t4.cno
NOT IN(SELECT t1.cno FROM course t1,teacher t2 WHERE t1.tno=t2.tno AND t2.tname='刘冰')
GROUP BY t3.sno
4、查询学过“6-166”并且也学过编号“3-105”课程的同学的学号、姓名；
SELECT a.sno,a.sname FROM (SELECT student.sno,student.sname FROM student ,score WHERE student.sno = score.sno
AND score.cno='6-166') a ,(SELECT student.sno,student.sname FROM student ,score WHERE student.sno = score.sno
AND score.cno='3-245' )b WHERE a.sno = a.sno GROUP BY sno
SELECT a.sno,a.sname FROM student a,(SELECT sno FROM score
WHERE cno='6-166' OR cno='3-105' GROUP BY sno HAVING COUNT(1)>=2) b WHERE a.sno=b.sno
5.查询至少有一门课与学号为“103”的同学所学相同的同学的学号和姓名；
SELECT a.sno,a.sname FROM student a,
(SELECT DISTINCT sno FROM score WHERE sno<>'103' AND cno IN (SELECT cno FROM score WHERE sno='103')
) b
WHERE a.sno =b.sno GROUP BY a.sno
练习所用,若有不妥,还请指教!!