sub foo {
    ...

    my %locations = &bar($dbh);

    ...
  
    my $location_text = $locations{$ref->{'location'}};
}

sub bar {

    my $dbh = shift;

    my $sql_loc = qq|SELECT * FROM ndmw_location|; 
	my $sth = $dbh->prepare($sql_loc); 
	$sth->execute or die("...");

    my %locations;

	while (my $ref = $sth->fetchrow_hashref())
	{
		my $id = $ref->{'id'};
		my $location =  $ref->{'location'};
        $locations{$id} = $location;
	}

	$sth->finish;

    return %locations;
}