What is the purpose of the cross-referencing design?

QUESTION: What is the purpose of the cross-referencing design?   [signinlocker] SOLUTION   The cross-referencing design is an alternative modeling approach that guarantees the absence of null values in the foreign key. It entails the creation of a relation schema to represent the relationship type. [/signinlocker]

What is the difference between the referencing relation schema and the referenced relation schema? How are these terms incorporated into the foreign key design?

QUESTION: What is the difference between the referencing relation schema and the referenced relation schema? How are these terms incorporated into the foreign key design?   [signinlocker] SOLUTION   The parent is the referenced relation schema and the child is the referencing relation schema (i.e., it references the relation schema that contains the primary key)….

What is a candidate key? How does a candidate key differ from a superkey?

QUESTION: What is a candidate key? How does a candidate key differ from a superkey?   [signinlocker] SOLUTION   A candidate key is defined as a superkey with no proper subsets that are superkeys. A candidate key has two properties: the uniqueness property and the irreducibility property, whereas a superkey possesses only the uniqueness property….