Formulating an sql query with CTID

Hi,
I have a query i am having trouble to formulate:
I used to do:
SELECT DISTINCT a0,a1 FROM public.t1
However, now i need to add the CTID attribute, but CTID is unique
thus, distinct is useless. In addition, i can't seem to be able to use max()
etc... or casting to anything on CTID in order to use group by technique.

What are my options?

(I am using 8.2 or 8.1)

--
Regards,
        Tzahi.
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Tzahi Fadida
Blog: http://tzahi.blogsite.org | Home Site: http://tzahi.webhop.info
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