Refining the Design
Consider the definition of the CustomerOrders entity shown in Figure 2.1 in more detail. Some of the items contained in the entity represent several data values. For example, CustomerAddress includes a street number, city, state, and ZIP code. Although they may be complicated, each item represents one chunk of information, except for ItemsOrdered. The CustomerAddress item contains several subfields, and you know exactly how many subfields every CustomerAddress contains. On the other hand, a single CustomerOrders record might need to hold many ItemsOrdered entries.
Figure 2.2 shows one attempt to model the CustomerOrders entity in more detail. In this version, the ItemsOrdered entity is broken into four separate entries. Each ...
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