Hi i am looking for the most performant way to ensure a unique username.
I did already check similar questions but none of them made me happy.
So here I came up with my solution. I appreciate your comments.

```
CREATE TABLE IF NOT EXISTS `user` (
`guid` bigint(20) unsigned NOT NULL AUTO_INCREMENT,

`firstname` varchar(48) NOT NULL,
`lastname` varchar(48) NOT NULL,
`username` varchar(128) NOT NULL,
`unique_username` varchar(128) NOT NULL,

PRIMARY KEY (`guid`),
KEY `firstname` (`firstname`),
KEY `lastname` (`lastname`),
KEY `username` (`username`),
UNIQUE KEY `unique_username` (`unique_username`),
UNIQUE KEY `email` (`email`)

) ENGINE=MyISAM AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

```

`username` contains `firstname.lastname` without numeric suffix while `unique_username` contains `firstname.lastname.(count of equal usernames)`

to get the count of equal usernames I am performing following query against the user table (in advance to the insert).

```
SELECT COUNT(*) FROM user WHERE username = 'username'

```

Unfortunately I can't use a lookup against `firstname and lastname` since they are case sensitive.