Question

What is Multiplicity Rule #4?

1) Whenever there are optional-minimums on both sides of a one-to-one relationship, create an association table linking the two entities
2) Whenever there are mandatory-minimums on both sides of a one-to-one relationship, or an optional-minimum on one side of a one-to-one relationship, the two entities should be combined into a single entity
3) Whenever there is a many-to-many relationship, (regardless of the minimum constraints), create an association table linking the two entities
4) Whenever there is a one-to-many relationship (regardless of the minimum constraints), place the primary key of the 'one' entity into the 'many' entity as a foreign key

Answer 1

Multiplicity Rule #4 concerns the structuring of a one-to-many relationship within a database, where the primary key of the 'one' entity is included as a foreign key in the 'many' entity's table.

Step-by-step explanation:

The question refers to the Multiplicity Rule #4 in the context of database design, specifically talking about entity-relationship (ER) modeling. When dealing with relationships between entities, certain rules help determine how to structure the database tables for optimal data representation and integrity. The correct answer to the question is option 4: Whenever there is a one-to-many relationship (regardless of the minimum constraints), place the primary key of the 'one' entity into the 'many' entity as a foreign key.

This rule facilitates the linking of multiple instances of one entity to a single instance of another entity. For example, if we have an entity called 'Author' and another entity called 'Book,' and each author can write many books, but each book can have only one author, we place the primary key from the 'Author' table into the 'Book' table to represent this one-to-many relationship.