As rare as 1:1 relationships should be, certain conditions absolutely require their use.

Question

Quizplus · Accepted Answer

There are certain situations where a 1:1 relationship between two entities is necessary, such as when each instance of one entity can only have one corresponding instance of the other entity, and vice versa. For example, in a database of employees and their Social Security numbers, each employee can only have one unique Social Security number, and each Social Security number can only be associated with one specific employee. In these cases, a 1:1 relationship is the most efficient and effective way to link the two entities.

As Rare as 1:1 Relationships Should Be, Certain Conditions Absolutely