$param =~ s/'(\d+)'/$1/g;
$param =~ s/NULL/undef/g;
@list_of_params = split /\s*,\s*/, $param;

##</code><code>##

$param =~ s/'(\d+)'/$1/g;
@list_of_params = map { ($_ eq 'NULL') ? undef : $_ }
                  split( /\s*,\s*/, $param );