This question is one of the frequently asked questions - "How do I loop through a tabular form using a dynamic action?". This example shows how to loop through a tabular form and set the values for each row to what ever you want. Using apex_application.g_fxx array is not an option for onload processes or dynamic actions. It can only be used in an on submit process. Using jQuery in a simple loop it is possible to read / set any of the values in any column. Try it out.