GATE 2017 CS (CS2) – Question 27
Entity types A and B are connected by relationship R with no attributes. When can the relation table for R be merged with A’s table?
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Correct answer: (C) R is many-to-one and A participates totally.
Explanation
For many-to-one A→B, every A entity has at most one related B. Total participation makes that exactly one, allowing its B key to be stored as a nonnull foreign key in A without a separate relationship table. This is the conventional merge condition C. A one-to-many relationship would require multiple B keys per A row.