filtering out doubles with SELECT - Mailing list pgsql-novice

Hello everyone,

I was wondering how to filter out double values (where "value" spans
two columns COL1 and COL2) with a SELECT statement. If I have this
table:

COL1 |COL2 |COL3
-----------------------------
a    |b    |some value
a    |b    |another value
a    |c    |yet another value

what would be the select statement to get this result:

COL1 |COL2 |COL3
-----------------------------
a    |b    |some value
a    |c    |yet another value

I was thinking that DISTINCT would do this, but I don't want to loose
COL3. TIA for any tips!