I'm writing to a file. There are only ten items able to be written to the file (game scores, test results, whatever). I'm using a drop-down selection list on the form to tell which number is being submitted. Is there any way to have it checked as the page loads what numbers have been submitted and omit them from the selection list? (Say numbers 1, 2, 4, and 8 have been submitted; then only 3, 5, 6, 7, 9, & 10 would be available.)
Also, how would I go about averaging something already submitted into the file with new data as it comes in? (An item that cost $2 is already in the file. An item that costs $1 is submitted. I want the average of $1.50 outputted. How would I accomplish this?)