A many-to-one relationship exists between entity sets r1 and r2 . How will it…

Answer: Pk(r1) → Pk(r2)

Why this is true:

• Definition: A many-to-one relationship from r1 to r2 means each tuple in r1 is associated with exactly one tuple in r2, while a tuple in r2 may be associated with many tuples in r1.

• Relational representation: The relation on the many side (r1) stores a foreign key that references the primary key of the one side (r2).

• Functional dependency: Because each r1 tuple refers to a single r2 tuple, the primary key of r1 uniquely determines the primary key of r2, giving the functional dependency Pk(r1) → Pk(r2).

• Contrast: Pk(r2) → Pk(r1) would mean each r2 tuple determines a single r1 tuple (the opposite direction), and having both directions would imply a one-to-one relationship.