Field restrictions on linked table "Please Help"

[SA812]

I have a form with a imbeded table in it. There is a one to many relatioship with the main form. I want to restrict the users from entering more that x number of records in the sub form/table. Also i would like some logic to prevent them from entering duplicate numbers. It cannot be a primary key, basically there scanning bar codes i just don't want them scanning the same bar code twice into the subform.

Thank You
SA

 

[wonderhands]

Every time they scan a new barcode use the dcount function return the count of records in the subset and also return the number of records that match the barcode.

DCount() - you can read about it in the Access Help Files