Question

Which of the following is true for a natural join between two relations \( R(A, B) \) and \( S(B, C) \)?

• A. Result is always a Cartesian product
• B. Common attribute B appears twice
• C. Result will have schema \( (A, B, C) \)
• D. Natural join cannot be performed unless attribute names differ

Hint:

In a natural join, common attributes are matched and appear only once in the result. Always check for schema compatibility before applying a natural join.

Answer 1

The Correct Option is C

A natural join combines two relations based on common attributes.
Given: \( R(A, B) \) and \( S(B, C) \), the common attribute is \( B \).
During a natural join: 
- Matching tuples from both relations based on the value of common attribute \( B \) are joined.
- The result includes all attributes from both relations, but the common attribute \( B \) appears only once.
Therefore, the resulting schema will be: \( (A, B, C) \), where: - \( A \) is from relation \( R \),
- \( B \) is the common attribute, and
- \( C \) is from relation \( S \).
This confirms that option (3) is correct.