>I've read a past thread about the way the locking is occuring based on APPEND BLANK, INSERT SQL, etc. There was a mention that INSERT SQL is better to use.
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>I use INSERT SQL a lot, for robot applications - not for desktop applications, and have found that sometimes, collisions occur. So, at the same time, the same INSERT SQL is executed by 2 applications. The 2nd one will have "File is in use by another user". What will be the best way to handle this so we can make sure that each application will process this locking in a queue?

I have never seen this before, but I guess the first thing you have to do is to check SET REPROCESS setting (should be AUTOMATIC). If you still will see the problem, you can proceed by old RLOCK() way (have separate Locker table with particular record locked when a user try to perform specific operation).