19、  查询选修“3-105”课程的成绩高于“109”号同学成绩的所有同学的记录。

select * from score where cno='3-105'and degree > (select degree from score where sno = '109'and cno='3-105');

20、 查询成绩高于学号为“109”、课程号为“3-105”的成绩的所有记录。

select * from score s where s.degree>(select degree from score s join course c on s.cno = c.cno where c.cno='3-105' and s.sno='109');

22、查询和学号为108的同学同年出生的所有学生的Sno、Sname和Sbirthday列。

select sno,sname,sbirthday from student where sbirthday = (select sbirthday from student where sno = '108');

23、查询“张旭“教师任课的学生成绩。

select degree from score s join course c on s.cno=c.cno join teacher t on c.tno=t.tno where t.tname='张旭';

25、查询95033班和95031班全体学生的记录。

select * from score e join student t on e.sno = t.sno where sclass in(95031,95033)