I want to enter an invoice
customer info and articles arrive by PHP
there will be a drop-down list with the codes of the customers and that there is selection the information such as address and other must be automatically displayed
and a drop-down list with the item codes and the selection and price must be displayed automatically.
the user can add another line of articles
at the end a calculation of the total amount the discount must be done automatically
and after that there is validation I get the information of one of php and mysql