Re: Help with the best table layout for message board

[Rick James]

VARBINARY(15) suffices for IPv4. 'nnn.nnn.nnn.nnn'

CREATE TABLE BlackList (
   ip VARBINARY(15) NOT NULL,
   PRIMARY KEY (ip)
);
SELECT COUNT(*) FROM BlackList WHERE ip = ? ;

In PHP you will get back 0 or 1 from the SELECT; act accordingly.

I don't see the need for further normalization.

A variation; assuming your table xyz has an ip VARBINARY(15) field, and

SELECT ...,
       IFNULL(xyz.ip, 'is blacklisted') AS status
   FROM xyz
   LEFT JOIN BlackList bl  ON bl.ip = xyz.ip

The 'status' column will either be the ip address or the string "is blacklisted".