Question

The table is called limits and takes the following fields:

id    |    ip    |    limit

on every page load, I’m checking if the user has a record in this table (determined by ip) and if they don’t, I insert a record. However if the record already exists, I don’t want to do anything.

I basically need a INSERT IF NOT EXISTS type query. I’ve already read this and the INSERT IGNORE example looks good but as far as I can tell it only works for primary keys. In my case the id field is the primary key and I want to check if the ip already exists.

Here’s some sort of pseudo SQL code:

INSERT INTO `limits` (ip, limit)
VALUES ('127.0.0.1', 8)
IF NOT EXISTS `limits`.`ip`

Thanks for any help!

EDIT: tried this too

INSERT IGNORE INTO `limits`
SET `ip` = ‘127.0.0.1′,
`limit` = 8;

Answer 1

INSERT IGNORE will ignore any unique indexes, whether it’s the primary key or any unique key.

You can create a unique key on IP using

ALTER TABLE limits
  ADD CONSTRAINT idx_limits_ip
  UNIQUE (ip)

The Manual has a few alternative syntax to create indexes.