Hi

I made a table with the FF fields:
NUMBER1 NUMBER2 SUM

Then I made a form using this table. The first 2 fields are entered by the user when the user hits enter the SUM field is populated by the sum of the 2 numbers.

I made an expression builder from the control source for this SUM field: ---> = [NUMBER1] + [NUMBER2]

My problem is when I look at the table I made the first 2 fields are populated but the SUM field ( which was a result of the expression I made) wasn't. Why is this so and how do make it to automatically save this field together with the other 2 fields?

Thank you!

To get the third field to populate, you need to put code out there. You can either put code on NUMBER2's After Update event that sums the two numbers or you can put something on the form's On Close event that sums it when you close it.

Note: It's never a good idea to store calculated fields. In this case, SUM is just NUMBER1 + NUMBER2. Don't store this because you're using up valuable memory. If you need SUM in the future, merely recalculate it. So really, the true answer to your question is don't store SUM at all! :D

Greg Serrano
Michigan Dept. of Environmental Quality, Air Quality Division

Greg thank you for the reply
i know that I need to put a code in the events properties ( after update etc..) however I dont know the syntax... I know it is an update code but I am not familiar with the syntax. Would you know the code or the syntax?

I need to store the SUM field because I need to a summation on this field whenever the user inputs a value. In other words, I need to do a another calulation just for the SUM field that is why I need to store this value in the table.

In the After Update event use something like:

Greg Serrano
Michigan Dept. of Environmental Quality, Air Quality Division

You really should read up on the concept of normalization. The first rule of normalization is that all data is atomic; that is, data is not repeated, and is not a composite made of other data elements.

The reason why this rule exists is that it is just too easy for such composite data to get 'out of sync' with the data which comprises it. If you have some process somewhere which updates, say, column NUMBER1 and doesn't 'remember' (or otherwise 'know') that NUMBER1 is not only a piece of data in its own right, but is also a component of some other column (e.g. SUM), then your data has just become corrupt. Worse, you'll have virtually no evidence that this data is wrong until somebody notices someday that things don't add up. You'll also have no idea which process or program caused the corruption or when it occurred, making for a very difficult debugging chore.

You claim you need this column because you have to sum on it, but it's a simple matter to sum the component columns as, e.g:
or otherwise include its components in any other expression.

Jeff Mason
Custom Apps, Inc.
www.custom-apps.com

Thank you for the Reply!