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Data Modeling Made Simple with CA ERwin Data Modeler r8 by Steve Hoberman, Donna Burbank

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1NF ensures that “Every data element must provide a fact about the key. Key refers to the primary key of the entity. ‘Provide a fact about’ is the key phrase, which we defined earlier and will elaborate on here. It means that for a given primary-key value, we can identify, at most, one of every data element that depends on that primary key. For example, assume Department Number is the primary key to the Department entity. Table 18.4 shows some sample values.

Table 18.4 Sample Values for Department

Department Number

Department Name

A

Accounting

A

Marketing

B

Information Technology

C

Manufacturing

In this example, Department Number A identifies two values for Department Name: Accounting and Marketing. Therefore, Department ...

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