Bill,

Two ideas come to mind, 1 your data is not in thrid normal form if you are storing the result of a calculation. That means it is not unusual to require the extra TableUpdate. 2 By violating third normal form you have created a sequence dependency on the tableupdates, the child must always be done first and the parent must always be done if the child was done.

When we choose to break a normalization rule we often pay with more complex code to handle integrity issues. The real question here is, "Is it better to store the total and have complex integrity code, or not store the total and have simple integrity code."

If you choose to not store the total, then you only have to calc it when it needs to displayed or printed. With SQL syntax that isn't always such a tough thing to do. It depends on the number of details any given parent might have.