SELECT * FROM STUDENT 
will return all students in STUDENT table

Question : What are the Subjects taught in School ?
Answer : ICT, PHYSICS, MATH, MEDIA, DRAMA, MUSIC

SELECT * FROM SUBJECT
This will return all Subjects from SUBJECT table

Question : What are the marks of Nimal ?
Answer : ICT=77, PHYSICS=75, MATH=65

To obtain this data we have to JOIN STUDENT, SUBJECT and MARKS Tables

SELECT stNo, subNo, Marks FROM MARKS WHERE  stNO=1
This will return 3 records from MARKS Table

However we will not have Student Name and Subject Name in the result. They have to be obtained from STUDENT and SUBJECT tables.

WE Need to write a Join Query for this purpose.

select STUDENT.Name, MARKS.Marks, SUBJECTS.subject from Marks
inner join STUDENT on MARKS.stNo = STUDENT.stNo
inner join SUBJECT on MARKS.subNo = SUBJECTS.subNo;