Question

Which one of the options given below refers to the degree (or arity) of a relation in relational database systems?

• A. Number of attributes of its relation schema.
• B. Number of tuples stored in the relation.
• C. Number of entries in the relation.
• D. Number of distinct domains of its relation schema.

Hint:

Remember: In DBMS — Degree = Number of attributes (columns), Cardinality = Number of tuples (rows). This distinction often appears in exams.

Answer 1

The Correct Option is A

In the context of relational database systems, the term "degree" (or "arity") refers to a specific property of a relation. Let's examine the given options one by one to determine the correct answer:

1. Number of attributes of its relation schema: The degree (or arity) of a relation is defined as the number of attributes (columns) it has. Hence, this option is correct. If a relation has five attributes, its degree or arity is five.
2. Number of tuples stored in the relation: This refers to the cardinality of the relation, which is the number of records or rows in the table, not the degree.
3. Number of entries in the relation: This term is not generally used in database terminology to define the degree. It is more related to describing the total number of individual data points, which is not the same as degree.
4. Number of distinct domains of its relation schema: Domains refer to the set of allowable values for a given attribute, which does not directly correlate to the degree of the relation.

Conclusion: Based on the analysis, the correct answer is the Number of attributes of its relation schema, as this defines the degree (or arity) of the relation in a relational database system.