my @octets=split(/\./,$ip_address);
my $numerical_address=($octets[3]+(255*$octets[2])+(65535*$octets[1])+(16777216*$octets[0]));

##</code><code>##

SELECT count(*) from table WHERE (int(ip/256)*256) = (int($ip_address_to_be_compared_to/256)*256)