Database

Users
user_id
user_name

data
1,Demo1
2,Demo2
3,Demo3
4,Demo4
5,Demo5
6,Demo5

Groups
group_id
group_user_id (Users.user_id who owns this group)
group_name

data
1,1,Design
2,1,Support
3,1,Sales
4,2,tmp_demo2

Groupmembers
groupmember_group_id (Groups.group_id)
groupmember_user_id (Users.user_id)

data
1,2
3,2
1,4

SELECT     Users.user_id, Users.user_name, Groups.group_name
FROM         Users LEFT OUTER JOIN
                      Groupmembers ON Users.user_id = Groupmembers.groupmember_user_id LEFT OUTER JOIN
                      Groups ON Groupmembers.groupmember_group_id = Groups.group_id AND Groups.group_user_id = 1

1	demo1	Design
1	demo1	NULL
2	demo2	NULL
3	demo3	Support
4	demo4	NULL
5	demo5	NULL
6	demo6	NULL

foreach (DataSetCollege.GradesRow var in grades)
{
     Response.Write( var.grade + var.CoursesRow.crsName);
}