When selecting a foreign key placement for a 1:1 relationship, place the PK of the entity on the mandatory side in the entity on the optional side as a FK, and make the FK mandatory when .
A) one side is mandatory and the other side is optional
B) one side participates in another relationship
C) both sides are optional
D) both sides are mandatory

Question

Quizplus · Accepted Answer

When one side of the 1:1 relationship is mandatory and the other side is optional, we should place the PK of the entity on the mandatory side in the entity on the optional side as a FK and make the FK mandatory. This is done to ensure that there is always a record in the optional entity for the mandatory entity.

When Selecting a Foreign Key Placement for a 1:1 Relationship