Page 1424 - (ISC)² CISSP Certified Information Systems Security Professional Official Study Guide

FIGURE 20.7 Hierarchical data model

The hierarchical model in Figure 20.7 is a corporate organization
chart. Notice that the one-to-many data model holds true in this
example. Each employee has only one manager (the one in one-to-
many), but each manager may have one or more (the many)

employees. Other examples of hierarchical data models include the
NCAA March Madness bracket system and the hierarchical
distribution of Domain Name System (DNS) records used on the
internet. Hierarchical databases store data in this type of hierarchical
fashion and are useful for specialized applications that fit the model.
For example, biologists might use a hierarchical database to store data

on specimens according to the
kingdom/phylum/class/order/family/genus/species hierarchical
model used in that field.

The distributed data model has data stored in more than one database,
but those databases are logically connected. The user perceives the
database as a single entity, even though it consists of numerous parts

interconnected over a network. Each field can have numerous children
as well as numerous parents. Thus, the data mapping relationship for
distributed databases is many-to-many.

Relational Databases

A relational database consists of flat two-dimensional tables made up