Retrieve octets from IP addresses

from the Artful Common Queries page

If ip is for the form N.N.N.N where N may be 1, 2 or 3 digits, how to group and count by just the first three octets, ie the ip class? 

SELECT 
  LEFT(ip, CHAR_LENGTH(ip) - LOCATE('.', REVERSE(ip))) as ipclass,
  COUNT(*)
FROM tbl
GROUP BY ipclass;
Hamilton Turner notes we can find the first octet with LEFT(ip,LOCATE('.',ip)-1).

Last updated 15 Jan 2025