Cristi,
> salt=> SELECT da FROM a WHERE da =
> to_date('03-31-2002','MM-DD-YYYY');
> ERROR: No such function 'to_date' with the specified attributes
>
> salt=> SELECT da FROM a WHERE da = (DATE '2002-03-31');
> 03-30-2002
> 03-30-2002
<snip>
> 03-30-2002
> (1808 rows)
Please post both your postgres version and your actual CREATE TABLE
statement.
-Josh Berkus