Q85185.
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. BankAccount_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?
- (1) BankAccount_Number is a candidate key
- (2) Registration_Number can be a primary key
- (3) UID is a candidate key if all students are from the same country
- (4) If S is a superkey such that S U ID is NULL then S U ID ∩ U is also a superkey
