COMPUTER APPLICATIONS
DATABASE MANAGEMENT SYSTEMS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Which one of these cannot be taken as a primary key?
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ID
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registration no
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Department ID
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Street
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Explanation:
Detailed explanation-1: -Which one of the following cannot be taken as a primary key? Explanation: Street is the only attribute which can occur more than once.
Detailed explanation-2: -To qualify as a primary key for an entity, an attribute must have the following properties: It must have a non-null value for each instance of the entity. The value must be unique for each instance of an entity. The values must not change or become null during the life of each entity instance.
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