I need an automatic order processing script to be made for my store.
I will create the IPN script, so that's not needed for you to create.

What you need to make:
There will be mysql tables storing serial numbers. I will always upload serials when they are getting sold out, so no problem with that. The IPN script will pass the serial type (basic, premium, ultimate) and your script will take one serial out of the matching table, put it into History, and send details to user in e-mail.
Also I need you to create a script, which ppl need to enter their e-mail address into it, and will send all previous orders matching that e-mail address, to the e-mail. In one e-mail, not 1by1.

Please also make the mySQL table using the following details:
Table: History
Fields: ID, e-mail address, serial number
Table: Basic
Fields: ID, serial number
Table: Premium
Fields: Id, serial number
Table: Ultimate
Fields: Id, serial number

I also need a simple subroutine which I can add into my already made script which will do the following:
It will check the selected table in mysql, and return the number of available serials.
I will do the integration, you only need to make the mysql request for it.