Database Systems 6th Edition by Ramez Elmasri, Shamkant B. Navathe

Exercise 2

Database design often involves decisions about the storage of attributes. For example a Social Security Number can be stored as a one attribute or split into three attributes (one for each of the three hyphen-deliniated groups of numbers in a Social Security Number-XXX-XX-XXXX). However, Social Security Number is usually stored in one attribute. The decision is usually based on how the database will be used. This exercise asks you to think about specific situations where dividing the SSN is useful.