Insert Multiple rows in a single column in mySql

Question

I have a table called class in that I have three columns "Name", "Roll Number" and "Subject". Now the Name & Roll Number columns have 50 records each like

"Name"   "Roll Number"  "Subject" 
John       1              Null
Mark       4              Null 
Steeve     5              Null
Riya       2              Null

Now I want to insert data in the column, that is a different subject for different roll numbers like

"Roll Number" "Subject" 1 Maths 4 Computers 5 Music 2 Biology