For the M-O (parent mandatory,child optional)case,what action(s)should be taken to ensure minimum cardinality is maintained?
A)Define referential integrity constraint from child to parent
B)Make foreign key NOT NULL
C)Will require trigger or other application code
D)Both A and B are correct

Question

Quizplus · Accepted Answer

To ensure minimum cardinality is maintained in the M-O case, we should define a referential integrity constraint from the child to parent and make the foreign key NOT NULL. This can be achieved by selecting both options A and B, which will enforce the relationship between the parent and child tables and prevent any child rows from existing without a corresponding parent row. This can ensure that the minimum cardinality is maintained as per the requirements of the business logic. Option C is not necessary to maintain minimum cardinality in this case, as it may depend on the specific requirements of the application being developed.

For the M-O (Parent Mandatory,child Optional)case,what Action(s)should Be Taken to Ensure