prevent phpmyadmin redunduncy of data

Question

I am to create an enrollment system and I have the following tables in my database:

Subject //Primary key: Subj_no
Student //Primary key: Stdnt_no
Subject_Student //Primary key: Subj_Stdnt_no

Where Subject_Student is related(indexed) to Subject and Student with their primary keys.

Now my question is: How can I prevent the database from making the same relationship again? Example> For say I have the following rows inside Subject_Student:

Subj_Stdnt_no | Subject |  Student 
      1       |    1    |     2
      2       |    1    |     6
      3       |    1    |     2       <------How can I prevent that? It's redundant.

Answer 1

PhpMyAdmin is a query tool for mysql, not a database.

You'll want to make the combination of (Student, Subject) UNIQUE.

Answer 2

I've managed to answer my own question through thew help of @Femaref I used: ALTER TABLE Subject_Student ADD UNIQUE (Subject,Student);