my $sth;
my @columns = qw( col1 col2 col3 col4 col5 col6 );
{   local $" = ",";
    $sth = $dbh->prepare (
        "select @columns ftom table where day = '10-08-2007' order by col3, col4");
    }
$sth->execute;
while (my $row = $sth->fetchrow_hashref) {
    ...
    }