DATA ADMINISTRATION, DATABASE ADMINISTRATION, AND DATA DICTIONARIES - Fundamentals of Database Management Systems - page 286

• Table (or file) Construction: Which attributes (or fields) appear in which
tables (or files).
• Security: Which people have access to which databases or tables or files.
• Impact of Change: Which programs might be affected by changes to which
tables or files. ( Note: This has become much less of an issue due to the data
independence of relational databases.)
• Physical Residence: Which tables or files are on which disks.
• Program Data Requirements: Which programs use which tables or files.
• Responsibility: Which people are responsible for updating which databases
or tables or files.

F IGURE 10.9
Data dictionary sample relationships

record or table row, the Home Address of a person, the Capacity of a disk, the
Language that a program is written in, and so forth.

Relationships The relationship between almost any pair of data dictionary entities
can have value to IS management. Some examples of common data dictionary
relationships and the entities involved are shown in Figure 10.9. With such
relationships between the dictionary entities, data administration personnel can aid
in new software development, data security and privacy, change management, and
do a host of other IS environment tasks.

Uses and Users Data dictionaries can be of considerable use to a variety of people in
the corporate environment in general, as well as in the IS environment specifically.
Clearly, the heaviest users of the data dictionary will be IS management and the
data administration and database administration functions under them. The data
dictionary is fundamentally the database used to store the data about the data and
computer resources that these various people are charged with managing. Whether
producing periodic lists of databases or tables in the IS environment or responding to
ad hoc queries about which personnel had access to leaked data, the data dictionary
is the information resource for IS.
Systems analysts and program designers use the data dictionary in two major
ways. One is as a source of information about what entities, attributes, and so forth
already exist in the IS environment that might be needed in a new application
development effort underway. If the data needed for a new system already exists,
then the new application may be able to use it. If there are existing database
structures that the application can add on to in order to satisfy its requirements, then
that might yield a large cost saving. In those and related situations, the dictionary
is the repository of data to be searched. The other use of dictionaries for systems
analysts and designers is as a documentation device for the new information that is
generated as a result of their application development efforts. In this way, application
developers have a natural vehicle for documentation and the data dictionary has a
natural way of being populated with data concerning new applications.
Corporate employees in all functions and at almost all levels can benefit
from the data dictionary by using it to discover the data available in the company.
Exploring new ways to use the data to improve their own responsibilities will help
the company as a whole. Finally, there is the benefit to corporate management. As
we said earlier, it becomes increasingly important for management to understand
the nature of the data in its systems, which mirrors the workings of the organization,
in order to have the best grasp on how the company functions.