An aggregation association is drawn using which symbol?
(A) A line which loops back on to the same table
(B) A small open diamond at the end of a line connecting two tables
(C) A small closed diamond at the end of a line connecting two tables
(D) A small closed triangle at the end of a line connecting two tables
Answer: (B)
Explanation: Association is a relationship where all objects have their own lifecycle and there is no owner.
Aggregation is a specialised form of Association where all objects have their own lifecycle, but there is ownership and child objects can not belong to another parent object.
Composition is again specialised form of Aggregation and we can call this as a “death” relationship. It is a strong type of Aggregation. Child object does not have its lifecycle and if parent object is deleted, all child objects will also be deleted.
So, option (B) is correct.
See: Association, Composition and Aggregation
Quiz of this Question