General :: Keeping Record Of Voucher Code

I am currently in the middle of creating a database as a means of keeping records of vouchers codes. When someone uses a voucher, I will then be able to input the name of the customer with the voucher code in the form.

This is meant to do two processes:

1. Keep a record of who has used a voucher
2. Check and validate the voucher code (the codes are kept in a table).

Now, I have created 90% of the db to input the customers details etc BUT...I am struggling for the validation part. Ideally, the db would also remove the said voucher code from the table so the same voucher code can not be used more then once.

I was going to "pre-install" the voucher codes in the db and then print off the vouchers for distribution. But I am basically tying to make the system so that it cannot be abused (for obvious reasons)...