What is a super key in a relational database? MCQ with Answer and Explanation

Question
What is a super key in a relational database?
A. A key that has extra attributes beyond a candidate key
B. A set of attributes that uniquely identifies a row
C. A key that includes the primary key
D. Both A and B
Answer: Option D
Solution (By JKExamLibrary)
A super key is a set of one or more attributes that uniquely identifies a row. A candidate key is a minimal super key.
This question belongs to: Computer Database Management System (DBMS)

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Practice More Database Management System (DBMS) Questions

Question #1
What is an attribute called when it can hold more than one value for a single entity instance, such as multiple phone numbers for a person?
A. Multi-valued Attribute
B. Derived Attribute
C. Complex Attribute
D. Composite Attribute
Discuss

Correct Answer: Option A

Explanation:
A Multi-valued Attribute is an attribute that can store multiple distinct values for a single entity instance (e.g., skill_set, phone_numbers).
This question belongs to: Computer Database Management System (DBMS)
Question #2
What is the purpose of the SQL 'DEFAULT' constraint?
A. To set a foreign key
B. To provide a default value for a column when no value is supplied
C. To enforce uniqueness
D. To define a primary key
Discuss

Correct Answer: Option B

Explanation:
DEFAULT assigns a default value to a column if an INSERT statement does not specify a value.
This question belongs to: Computer Database Management System (DBMS)
Question #3
Which of the following is NOT an aggregate function in standard SQL?
A. COUNT()
B. SUM()
C. AVG()
D. LENGTH()
Discuss

Correct Answer: Option D

Explanation:
SUM(), AVG(), and COUNT() are aggregate functions operating on multiple rows, whereas LENGTH() is a scalar function acting on a single text value.
This question belongs to: Computer Database Management System (DBMS)
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