To change the minimum cardinality on the parent side from zero to one,the foreign key,which would have been NULL,must be changed to NOT NULL.

Question

Quizplus · Accepted Answer

This is true because for a minimum cardinality of one on the parent side, each parent must have at least one child. In order to enforce this, the foreign key on the child side (which references the parent) must not be allowed to be NULL. Therefore, it must be changed to NOT NULL.

To Change the Minimum Cardinality on the Parent Side from Zero