Grouping data by multiple check boxes

[thhakala]

I have this table, which has several 1/0-fields (true/false). Simplified example of the table:
ID, C-1, C-2, C-3, C-4
1, 0, 1, 1, 0
2, 1, 0, 0, 0
3, 0, 1, 0, 0

I would need a report that groups the data by the selected C-N values. Example report:

C-1:
ID: 2
C-2:
ID: 1
ID: 3
C-3:
ID: 1

Any ideas how to do this simply, and without altering the table structure?
Thanks in advance!