In an Entity-Relationship (ER) model, suppose R is a many-to-one relationship from entity set E1 to entity set E2. Assume that E1 and E2 participate totally in R and that the cardinality of E1 is greater that the cardinality of E2.
Which one of the following is true about R?
(A) Every entity in E1 is associated with exactly one entity in E2.
(B) Some entity in E1 is associated with more than one entity in E2.
(C) Every entity in E2 is associated with exactly one entity in E1.
(D) Every entity in E2 is associated with at most one entity in E1.
Answer: (A)
Explanation: Since given relation is many to one :
Therefore, no entity in E1 can be related to more than one entity in E2 and an entity in E2 can be related to more than one entity in E1.
Only option (A) is correct.
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