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Consider a relational table with a single record for each registered student with the following attributes:
1. Registration_Number: Unique registration number for each registered student
2. UID: Unique Identity Number, unique at the national level for each citizen
3. Bank Account_Number: unique account number at the bank. A student can have multiple accounts or joint accounts. This attributes stores the primary account number
4. Name: Name of the Student
5. Hostel_Room: Room number of the hostel
Which of the following options is incorrect?
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- Bank Account_Number is a candidate key
- Registration Account_Number can be primary key
- UID is a candidate key if all students are from the same country
- If S is a superkey such that S UID ∩ is NULL then S UID is also a super key
- Bank Account_Number is a candidate key
Correct Option: A
Candidate key cannot be commen. Here, the two students can have common account number, so bank account number will not work like candidate keys.
