Making a PurchaseOrder form

[blueraincoat]

Hi Guys,
I'm working on a purchase order form. The PK of tblpurchaseorder is PO(purchase order) & PN(part number).
I want the form to be something like a report, I mean when you key in the first item, it stayed in the form, and you just moved to a new row and key in another item. So I made a subform basing on the tbl, and I embeded it into another form which is the attachment by the end. I do not want to key in the PO every time so i put it in the main form, but something must be wrong since everytime i move the focus from the PO to the PN, system gives me a warning that the PK should not be null.
The basic intention is that I don't want to key in the same PO every time.
Thanks in advance!

[jzwp11]

If many parts are associated with a purchase order, then you have a one-to-many relationship which requires 2 tables a purchase order table and a related detail table. The following is a typical table structure for a purchase order system.

tblPurchaseOrder
-pkPurchaseOrderID primary key, autonumber
-txtPurchaseOrder
-dtePurchaseOrder (date of purchase order)
-fkSupplierID foreign key to tblSuppliers

tblPODetails
-pkPODetailID primary key, autonumber
-fkPurchaseOrderID foreign key to tblPuchaseOrder
-fkPartNumberID foreign key to tblPartNumbers
-Qty
-unitPrice

tblPartNumbers
-pkPartNumberID primary key, autonumber
-txtPartNumber
-txtPartDescription

[blueraincoat]

Thank you very much jzwp11.
It's a very clear idea! Never thought it could be this easy.
One addtional question, would it be OK that I don't use auto number in all these tables? For some reason the auto number seems uncontrolable to me ...

[jzwp11]

Technically the primary key does not need to be an autonumber field, I just like to use them so I don't have to worry about it. The general rule is that the primary key should have no significance to the user, but there has been a lot of discussions on that. Additionally, it is best if the primary key is numeric since relational databases are more efficient with numeric fields in terms of matching and searching compared to text fields.

[blueraincoat]

Thanks for the detailed explanation.

[jzwp11]

You're welcome; good luck with your project.