Windows mutex to prevent multiple instances

[Dennis Lee Bieber]

Hans Nowak fed this fish to the penguins on Wednesday 28 August 2002 
05:31 pm:

> 
> It is important because the programs query the database, then write 
some stuff 
> back; running it multiple times simultaneously can (and obviously 
will, as we 
> have found) result in undesirable duplicate records.
> 

        Sounds more like you need to implement locking on the database side, 
not the client side. What type of database? (IE, custom file or actual 
DBMS).

        Perhaps use an intermediate daemon -- only the daemon talks to the 
database, the clients talk to the daemon (TCP/IP connections perhaps, 
with an inactivity time-out). If the daemon only accepts one connection 
at a time, the others should block or fail in some way.

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