Perfex database fix

I am using Perfex CRM and a MySQL database. I need a loop routine that must select my data within a date range read the record find the correct price do a calculation and update the same record in the table and then move to the next till all us done. I require this as a option on the menu that we can reuse at any time. Must be able to work live online on my server as we will not be sharing the application or database to any outside person