Hi Cyril

>A back to basics question please.
>
>A table only ever has one record with three fields, dt1, dt2, dt3.
>In a multi-user environment, users will update one of these fields.
>
>Example:
>
>User 1: changes dt1.
>User 2: changes dt2.
>
>Here is the problem: When user 2 saves the changes to dt2, the changes made by user 1 to dt1 are lost.
>
>How do I ensure that all changes are accumulative. The last user to update a particular field (say dt3) should stick, but any changes made in the meantime by other users to dt1 or dt2 should not be overwritten when dt3 is saved. How can that be achieved?

Optimistic techniques require you to expect everything will work fine. You give a warning if they don't. See Andy Kramek's point #4

http://weblogs.foxite.com/andykramek/archive/2005/12/27/1077.aspx

There is no need for row buffering. Look at the following and search for

"So what mode of buffering should I use in my forms?"

http://weblogs.foxite.com/andykramek/archive/2005/10/18/948.aspx

replace dt1 with datetime() record 1 in showdate
IF NOT TABLEUPDATE(.T.,"showdate")
  aerror(laError)
  MESSAGEBOX(laError[1,2])
ENDIF

You can refresh the form if that error happens. The current user then sees the current state of the form and decides if s/he wants still wants to change it.

This is exactly the same as if the current user never got the error. Because if another user made the same change 10 minutes ago, the current user would be deciding what to do with the current record.

Mike