Create a script for accessing a MySQL database.

I have an MySQL database on shared godaddy linux server.? I want to have users be able to upload a .csv file that has data in column A (specifically email addresses) then for them to be able to download a .csv file that has the same data in column A, but with additional data in columns B, C, etc. (ages, locations, etc.) that is obtained from the database. The database may not? necessarily? have all of the information for all of the cells or even have the email address in it, so for those instances I'd like the cells to be blank. All of this will be done on a website.