[Schlarman]

If you have a website and know PHP, SQL, ... it's pretty simple to figure out on your own.

Which do you think would work better; Django or PHP?

I personally know that PHP has been around longer and has a larger community, which means that more tutorials and documentation exists for it and it wouldn't be super hard to find help for it.

For what you are trying to do you can just google Random String Generator PHP on google and you will find this as one of the first links, it is a stack overflow answer and it gives you a PHP function to randomly generator a string I recommend setting it to a length of 7 then you can create a database with a table called codes ( or whatever you want really ) and have and ID (with auto increment on) then a spot for the code to be set (Put it as a varchar with a length of 7) then create that, head over to w3schools PHP Tutorials you can use this and find out how to connect to your database, select rows in a table to see if it exists, and how to insert information into it.

Have fun, if you got any questions just ask.