SQL练习

--18.
create table grade(low number(3),upp number (3),rank char(1));
insert into gGrade values(90,100,'A');
insert into grade values(80,89,'B');
insert into grade values(70,79,'C');
insert into grade values(60,69,'D');
insert into grade values(0,59,'E');

grade表：

select SNO,CNO,rank from t_hq_score,grade where DEGREE between low and upp;

--19.
select * from t_hq_score where CNO='3-105'and degree >all(select degree from t_hq_score where SNO='109');

--21.
select * from t_hq_score where DEGREE >(select degree from t_hq_score where cno='3-105'and sno='109');

--22.
--最初
select sno,sname,sbirthday from t_hq_student where sbirthday in (select sbirthday from t_hq_student where sno='108');
--改过后
select sno,sname,sbirthday from t_hq_student where to_char( sbirthday,'yyyy' ) = to_char( (select sbirthday from t_hq_student where sno='108'),'yyyy');

--23.
select * from t_hq_score where cno in(select cno from t_hq_course where tno in(select tno from t_hq_teacher where tname='张旭'));

--24.
select tname from t_hq_teacher where tno in(select tno from t_hq_course where cno in (select cno from t_hq_score group by cno having count(*)>5));