Storing IP address in MySQL database (IPv4 AND IPv6)

There is no integral type in MySQL big enough to store an IPv6 address. The most compact way to store it is as something like BINARY(16). If you just need to store and retrieve addresses and you don't need to perform logical operations on them (e.g. netmask operations to query for which IP addresses come under a covering prefix) then that will be enough. If you need to do logical or bit operations, you will need to be fancier: you will need to store IPv6 addresses in two separate 64-bit integer columns.

I use VARBINARY(16) for the data type and use the MySQL function INET_ATON() to insert the IP number (which I later read using the reverse function, INET_NTOA().

To store an IPv4 you can use an INT UNSIGNED, while for a IPv6 you need a decimal(39,0), to store an ip in the table you can use the function INET_ATON:

INSERT INTO table (ipcol) VALUES (INET_ATON('192.168.0.10'));

and retrieve it back with the function INET_NTOA:

SELECT INET_NTOA(ipcol) AS ip FROM table;

This answered existing before MySQL IPv6 support; users should be made aware that MySQL now natively supports IPv6: https://dev.mysql.com/doc/refman/5.6/en/miscellaneous-functions.html