Another thought would be to put a flag in your database that a waking process would check to see if there was another process already running.

Just as an aside, I once wrote an application similar to what you are describing where the client invoked CGI program did not directly update the database. Instead the updates were put into a staging table along with information telling another script who placed the updates there in the queue and another periodically run script did the actual updates. Additionally the client scripts would send a signal to the daemon that most of the time was ignored except when the daemon was "sleeping"

Now you are on XP so I don't know how this concept would port to your environment. If the concept of a service from NT made it over then your daemon would be a service.

Another scheme would be to write the updates to a spool directory and let your service pick up the updates from there and process them accordingly.