Deleting Duplicate Records in a Form

[Josef]

hi,

i have a form with 4 fields. when trying to add new records in a form i
am not notified if i am adding duplicates.

is there any way of detecting when a duplicate record is going to be
added and how can i notify the user and clear the form before a record
has been added.

i have set an autonumber that defines the record.

i would like the procedure to detect for duplicates after an item has
been selected from the last field and the user presses the enter key.

thx