Prefix-Postfix-Expression
November 23, 2024TNPSC-2012-Polytechnic-CS
November 26, 2024Candidate-key
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Question 1
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Consider a relational table with a single record for each registered student with the following attributes.
- 1. Registration_Num: Unique registration number
of each registered student
2. UID: Unique identity number, unique at the
national level for each citizen
3. BankAccount_Num: Unique account number at
the bank. A student can have multiple accounts
or join accounts. This attribute stores the
primary account number.
4. Name: Name of the student
5. Hostel_Room: Room number of the hostel
Which one of the following option is INCORRECT?
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BankAccount_Num is a candidate key
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Registration_Num can be a primary key
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UID is a candidate key if all students are from the same country
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If S is a superkey such that S∩UID is NULL then S∪UID is also a superkey
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Question 1 Explanation:
In case two students hold joint account then Bank Account_Num will not uniquely determine other attributes.
Correct Answer: A
Question 1 Explanation:
In case two students hold joint account then Bank Account_Num will not uniquely determine other attributes.