Not to long ago, I had a query regarding the best way to store IP addresses
in a DB, and make sure that they are unique.
It was pointed out to me that I could use four smallint columns instead of a
varchar to store these numbers, and just implement a UNIQUE index across all
four columns to make sure the combination of the four columns, would never
be in duplicate.
It seems, the UNIQUE index however still insist on having unique values for
all of the four columns...
The DB looks like this (the four smallint columns):
ALTER TABLE `domains` ADD UNIQUE `NS1_Unique`
Duplicate entry '127-30-127-1' for key 2
Which, tells me that I can have the following:
a, b, c, d - works
b, c, d, e - works
a, b, c, d - fails
a, a, b, b - fails <-- This should however not fail... (the combination is
Any idea on how I can get this working??