Help: a challanege SQL request

I have a table like this:
COL1 COL2

I                     a
I                     b
I                     c
II                    a
II                    b
III                   a
III                   b
III                   c

I would like to get all the col1 that data entry is the same as I.

So in this case, I has a, b, c, and III has a, b, c as well. I would like to get III, but II.

Could somebody help?

Thanks Received on Tue Jun 28 2011 - 14:50:42 CDT