TA Ch4 - Chapter 4: Entity Relationship Modeling Review...

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Chapter 4: Entity Relationship Modeling Review Questions: 1. What two conditions must be met before an entity can be classified as a weak entity? Give an example of a weak entity. The two conditions are that the entity is existence-dependent; it cannot exist without the entity with which it has a relationship, and the entity has a primary key that is partially or totally derived from the parent entity in the relationship. An example would be for an insurance company, an employee may or may not have a dependent, but the dependent must be associated with an employee; the dependent cannot exist without the employee. 3. Given the business rule "an employee may have many degrees," discuss its effect on attributes, entities, and relationships. (hint: remember what a multi-valued attribute is and how it might be implemented.) With this business rule "an employee may have many degrees" it can affect the other attributes, entities, and relationships within the conceptual model. If it is being
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This note was uploaded on 07/13/2011 for the course IST 210 taught by Professor Mcconn,charlotteryoo,jungwoo during the Summer '08 term at Penn State.

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TA Ch4 - Chapter 4: Entity Relationship Modeling Review...

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