How to create a token

[John Doe]

Hello,

I use 'INSERT IGNORE INTO' to create an account within my table. One variable is a token. Very important is - of course - that the token should be unique. But if the token already exists it should create the token-string as often as it takes for it to be unique. And then insert the data into the table.

Is there a query-command which could be helpful for my purpose.

I am thankful for every hint, link or even ready written script ;-)

Sebastian