COMPUTER APPLICATIONS
DATABASE MANAGEMENT SYSTEMS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Consider attributes ID, CITY and NAME. which one of these can be considered as a primary key?
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NAME
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ID
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CITY
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ID, NAME
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Explanation:
Detailed explanation-1: -Consider attributes ID, CITY and NAME. Which one of this can be considered as a super key ? Explanation: Here the id is the only attribute which can be taken as a key.
Detailed explanation-2: -Candidate keys are those attributes that uniquely identify rows of a table. The Primary Key of a table is selected from one of the candidate keys.
Detailed explanation-3: -A Primary Key is the minimal set of attributes of a table that has the task to uniquely identify the rows, or we can say the tuples of the given particular table. A primary key of a relation is one of the possible candidate keys which the database designer thinks it’s primary.
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