If two users try to update the same record at the same time, one of two
things will happen.
(1) The "second" user will be unable to save their changes - that's called
"optimistic locking"; or,
(2) The second user won't be able to start typing their changes until the
first user has saved their changes - that's called "pessimistic locking".
This behavious is deliberate & necessary. It stops the second user's changes
from invisibily overwriting the first user's changes.
In versions of Access up to & including Access 97, when a record is locked
(during process (1) or (2) above), >all records< on the same 2Kb "data page"
are locked. That might be >no< extra records, >one< extra record, a few
extra records, or >many< extra records, depending on the record size & other
factors. So it is somewhat unpredictable.
In later versions of Access, it is possible to get true "record level"
locking, though I'm not sure how to ask for that. It is doubtless in online
help somewhere.
HTH,
TC
