Customer$/$Product database modeling

Things to consider:

Purchase order $($PO$)$: is a legal document "Contract" issued by the buyer $($customer$)$ to the supplier,

indicating specifications, quantities, shipping date & mode, prices and agreed terms and conditions.

Invoice: is a document issued by a supplier $($Vendor$)$ to a customer. It identifies both parties and, it

shows the description, quantities, prices shipment date & mode and the payment terms of the items

sold. It serves as a demand for payment if it issued after the PO legalized or it may be just a pro$-$

forma invoice.

Many Invoices maybe generated for a single PO$!$

Sample of PO and Invoice forms are included.

Part $1($Invoice DB$).$

Identify entities in invoice transaction

Identify entities' identifier

Identify business rules $($make assumption wherever is necessary$)$

Draw invoice ERD and add necessary and sufficient attributes to each entity

Part $2($PO DB$).$

Identify entities in PO transaction

Identify entities' identifier

Identify business rules $($make assumption wherever is necessary$)$

Draw PO ERD and add necessary and sufficient attributes to each entity

Bonus

Draw the ERD of the PO and Invoice database as a single database system $($consider you are designing