multiple row data from database into single row in gridview

Question

In c# asp.net , how to display multiple row data from database in to a single row in gridview 

eg:

Output which i want it to be:

StaffName     |    Role      |   GroupNumber
Adrian            |   Lecturer  |   1,2

Instead of:

StaffName     |    Role      |   GroupNumber
Adrian            |   Lecturer  |   1
Adrian            |   Lecturer  |   2