These questions use the INVOICE Database
1. What fields are used to establish the relationships between the four tables CUSTOMER, INVOICE, INVOICEITEM and ITEM?
CUSTOMER is linked to INVOICE by |
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INVOICE is linked to INVOICEITEM by |
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INVOICEITEM is linked to ITEM by |
CUSTOMER is linked to INVOICE by CustABN
INVOICE is linked to INVOICEITEM by InvoiceNo
INVOICEITEM is linked to ITEM by ItemNo
2. For each of the relationships, explain the relationship. For example the relationship between customer and invoice, is
CUSTOMER and INVOICE: a customer can have many invoices but an invoice only belongs to one customer (1-∞).
INVOICE and INVOICEITEM: An invoice can have many lines (each for a different item) but a particular line only appears on one invoice (1-∞).
INVOICEITEM and ITEM: An item can appear in many lines but each line only contains one item (∞-1).