join in sql

                                                       

   student table
   student_id===================>primary key
======================================================================================
   school table
   school_id===================>primary key
   student_id=================>foreign key
===============================================================================

   marks table
   enroll_id===================>primary key
   school_id===================>foreign key
=========================================================================================

 





SELECT  s.student_fname, s.student_mname, s.student_lname, sc.school_name, sc.school_level,m.marks, m.percentage, m.grade
FROM public.student s cross join school sc  cross join marks m

SELECT  s.student_fname, s.student_mname, s.student_lname, sc.school_name, sc.school_level,m.marks, m.percentage, m.grade
FROM public.student s inner join school sc on (s.student_id=sc.student_id)
inner join marks m on (sc.school_id=m.school_id)

SELECT  s.student_fname, s.student_mname, s.student_lname, sc.school_name, sc.school_level,m.marks, m.percentage, m.grade
FROM public.student s  join school sc on (s.student_id=sc.student_id)
join marks m on (sc.school_id=m.school_id)

SELECT  s.student_fname, s.student_mname, s.student_lname, sc.school_name, sc.school_level,m.marks, m.percentage, m.grade
FROM public.student s right join school sc on (s.student_id=sc.student_id)
right join marks m on (sc.school_id=m.school_id)

SELECT  s.student_fname, s.student_mname, s.student_lname, sc.school_name, sc.school_level,m.marks, m.percentage, m.grade
FROM public.student s left join school sc on (s.student_id=sc.student_id)
left join marks m on (sc.school_id=m.school_id)


SELECT  s.student_fname, s.student_mname, s.student_lname, sc.school_name, sc.school_level,m.marks, m.percentage, m.grade
FROM public.student s, school sc ,marks m where (s.student_id=sc.student_id and sc.school_id=m.school_id)