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" I can image almost no way, how, that could be a valid business rule. I would expect that if any program was setting the value to less than zero, the program almost surely has a problem. That, or negative values are valid, but perhaps only if representative of the SUM of those items on back-order; thus the app or a trigger ensures that corresponding data is kept in sync.? As the scenario is stated originally, yes, that is the best way. And the only way to get the effect, without ensuring no such updates are..."^^<http://www.w3.org/2001/XMLSchema#string>
<http://archive.midrange.com/midrange-l/201405/msg01084.html>