1.Model a set of typical family relationships— spouse, father, and mother—in a single 3NF relation. Also include nonkey attributes name and birth date. Assume that each person has only one spouse, one father, and one mother. Show foreign keys with dashed underlining. 2. Many database management systems offer the ability to enforce referential integrity. Why would
using such a feature be a good idea? Are there any situations in which referential integrity
might not be important?