Question on some kind of flag?

Hello all!

I have a textbox that hold a numeric value in it. Getting this value from
SQL. If the value goes up, I need a message box to pop up. But I also I
have another text box that you will also add to that value from a user input.
Again, still going throug SQL. So the value would also go up, but because
the value was added, not from the result of a calculation.

What is the best way to flag so amessage box would only pop up when a value
goes up as a result of a calculation, not from just adding more to it?

Thanks!

Rudy