I have to create database of student having different subjects and marks in respective subjects.

Now many students will many subjects so there is many to many relationship.

My database design:
Table 1:

Student table
(PK)Stud_id, Stud_name

Table 2:

Subject table
(FK)Stud_id, Sub_id, Sub_name, Marks.

Table 3:

Stud_Sub table
Stud_id, Sub_id

1) is this design is right or wrong?

2) Secondly i want to find name of the student who scored second highest marks.