[QUOTE=Liberal]
That would present some practical problems. Either an independent process would have to monitor data, running in a perpetual loop, thereby eating up CPU and database resources with constant nonstop queries, or else a select query would have to be examined each time a thread is opened, initiating a conditional update if certain tests were positive. The latter is more palatable than the former, but even if there were plenty of server to do it, users would have to watch carefully because they might not notice the “Closed” button at the bottom until they have already written out their masterpiece. And then we’d be right back here in the Pit with demands to find a better way.
[/QUOTE]
Those seem like somewhat inelegant solutions. If I were to design something like this, I’d run it as a batch process. If you’re talking about a 6-month gap, precision to the level of days should be fine. Just scan your db nightly or even weekly and lock the old ones. It still consumes CPU and all, but on a schedule instead of all the time.