[Oracle] join과 subquery 연습문제

1.

select * 
from student natural join enrol ;

2.

select student.stu_no, stu_name, sub_name, enr_grade
from student, subject, enrol
where student.stu_no = enrol.stu_no
	and subject.sub_no = enrol.sub_no ; 

3.

select sub_name, stu_no, enr_grade
from subject natural join enrol ; 

4.

select sub_name, stu_no, enr_grade 
from subject join enrol using(sub_no) ;

5.

select stu_name
from student, enrol
where student.stu_no = enrol.stu_no
	and enr_grade >= 70 ;

6.

select stu_name
from student, enrol
where student.stu_no = enrol.stu_no 
	and enr_grade >= 60 ;

7.

select stu_name
from student natural join enrol
where enr_grade <= 70 ;

8.

select sub_name, sub_prof 
from student, subject, enrol
where student.stu_no = enrol.stu_no 
	and enrol.sub_no = subject.sub_no
	and stu_name ='김인중' ;

9. // 모르겠음 

select sub_name, sub_prof
from subject natural join enrol join student on (stu_no)
where stu_name like '김인중' ;

10. 

 

30.

select student.stu_no, stu_name, enr_grade
from student, enrol, subject
where student.stu_no = enrol.stu_no 
	and subject.sub_no = enrol.sub_no
	and sub_name ='시스템분석설계' ;

31.