Since there are only 9 different major numbers, this is a very simple situation. There are several ways to deal with this.
It should be understood that the description can be extracted from tblMajor and should never need to be input by the user.
The easiest, and very likely the best solution, would be to display both the MajorNo and Description together in the MagorNo dropdown. To do this you merely need to concatenate the values as you retreive them from the database or as you add them as options in the dropdown.
Another approach is to add some javascript code to hold the descriptions, and a way to map the descriptions to the majorNo - which could be done with an array or other mechanism. You would then need to handle the click or change or whatever event (you will have to determine the correct event) of the Major Number dropdown with a little javascript to display the description of the currently selected Major Number.
An overkill approach would be to do this with Ajax. With only 9 major numbers to deal with, it is easy enough to simply pass the data along with each response. If you had thousands of items to deal with, you would probably want to use an Ajax solution.
It probably isn't as important as it used to be, but for any solution using javascript the user will need to have their browser enabled to use scripting. If you don't feel this is likely, or you must provide your page without javascript, then the first solution will still work.
Woody Z
http://www.learntoprogramnow.com