Chapter10(pdf) - KFUPM Open Courseware
Chapter10(pdf) - KFUPM Open Courseware
Chapter10(pdf) - KFUPM Open Courseware
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Definitions of Keys and Attributes<br />
Participating in Keys (2)<br />
• If a relation schema has more than one key, each<br />
is called a candidate key.<br />
• One of the candidate keys is arbitrarily designated<br />
to be the primary key, and the others are called<br />
secondary keys.<br />
• A Prime attribute must be a member of some<br />
candidate key<br />
• A Nonprime attribute t is not a prime attribute—<br />
t<br />
that is, it is not a member of any candidate key.<br />
Copyright © 2007 Ramez Elmasri and Shamkant B. Navathe Slide 10- 25
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