Tabular form - updating a value in another column Vol. 1

Just recently, I had a requirement from one of my customers to create a kind of a form similar to excel, where user could update particular columns and this update will be applied (calculated) to the other columns, before the form is submitted.

First, I tried the solution posted in the forum, where you need to loop through a table using html_CascadeUpTill and and then find the row position. In some constelations this didn't work (vertical report template). I decided to look for alternate solutions and found out that this can be done in a more transparent way by simply using apex_item package and the ROWNUM. Also, the javascript code you need to do the update is much more transparent and much easier to debug. I also created a validation process to make sure only numbers are entered and an update statement for saving the changes to the corresponding table.

If you want to see a working example, go to my ApEx Demo Appication. There, you will find the full code.