sub add_foo
{
    my @expected_fields = qw/bar blah/;
    my ( @insert_flds, @insert_vals );

    for my $f ( @expected_fields ) {
        my $v = shift;
        next unless ( defined( $v ) and length( $v ));
        push @insert_flds, $f;
        push @insert_vals, $v;
    }
    my $sth = $dbh->prepare_cached( 'insert into foo (' .
        join( ',', @insert_flds ) . ') values (' .
        join( ',', ('?') x @insert_flds ) . ')' );

    $sth->execute( @insert_vals );

    return $dbh->last_insert_id( undef, undef, 'foo_id' ));
}