Ahhh, you got me. I wasn't paying enough attention to the data in the table I was using and some of the pairs where not unique. Since it was returning less rows than the total number of rows for the table I was assuming that it was working. For the record...

-------------
SQL> select * from tabc;

COLUMNA COLUMNB
---------- ----------
asdf one
asdf two

SQL> select unique(columna), columnb from tabc where columna='asdf';

COLUMNA COLUMNB
---------- ----------
asdf one
asdf two

SQL>
-------------


so it is doing unique for the pair. Of course, either way it is of no help to the original poster.

-Mike