Question

Given a table containing dotted quad IPv4 addresses stored as a VARCHAR(15), for example:

     ipv4
--------------
 172.16.1.100
 172.16.50.5
 172.30.29.28

what’s a convenient way to SELECT all "ipv4" fields with the final two octets scrubbed, so that the above would become:

    ipv4
------------
 172.16.x.y
 172.16.x.y
 172.30.x.y

Target RDBMS is postgresql 8.4, but the more portable the better!

Thanks.

UPDATE: while I do appreciate (and do upvote) slick INET/CIDR answers, I am looking to produce a string output with non-numeric characters substituted for the final two octets. (And, again, the more portable the better!)

Answer 1

For postgres:

select regexp_replace('172.16.1.100', E'(.\\d+){2}$', '.x.y');