WBJECA 2025 — Computer PYQ
WBJECA | Computer | 2025Choose the correct statement:
Choose the correct answer:
- A.
An alternate key is a candidate key, that is not a primary key
(Correct Answer) - B.
An alternate key is a primary key, that is not a candidate key.
- C.
An alternate key is a candidate key, that is also a primary key
- D.
None of the above
An alternate key is a candidate key, that is not a primary key
Explanation
To represent the relationship between these keys mathematically, we can define the set of Candidate Keys as C and the set containing the Primary Key as {P}. Since the Primary Key is always a member of the Candidate Keys, we have {P}⊂C.
The set of Alternate Keys, denoted as A, is defined as:
A=C∖{P}
In simple terms, an Alternate Key is any candidate key that remains after the primary key has been designated.
Explanation
To represent the relationship between these keys mathematically, we can define the set of Candidate Keys as C and the set containing the Primary Key as {P}. Since the Primary Key is always a member of the Candidate Keys, we have {P}⊂C.
The set of Alternate Keys, denoted as A, is defined as:
A=C∖{P}
In simple terms, an Alternate Key is any candidate key that remains after the primary key has been designated.