Database Reference
In-Depth Information
systems to produce information to help manage the enterprise. Such applications do not gener-
ate new data, but instead summarize existing data to provide insights to management. Digital
dashboards and other reporting systems assess past and current performance. Data mining
applications predict future performance. We will consider such applications in Chapter 12.
The bottom line is that database technology is used in almost every information system and
involves databases ranging in size from a few thousand rows to many millions of rows.
By The Way
Do not assume that just because a database is small that its structure is
simple. For example, consider parts distribution for a company that sells
$1 million in parts per year and parts distribution for a company that sells $100 million
in parts per year. Despite the difference in sales, the companies have similar data-
bases. Both have the same kinds of data, about the same number of tables of data,
and the same level of complexity in data relationships. Only the amount of data varies
from one to the other. Thus, although a database for a small business may be small, it
is not necessarily simple.
As shown in Figure 1-6, a
database system
is typically defined to consist of four components:
users, the database application, the database management system (DBMS), and the database.
However, given the importance of
Structured Query Language (SQL)
, an internationally recog-
nized standard language that is understood by all commercial DBMS products, in database pro-
cessing and the fact that database applications typically send SQL statements to the DBMS for
processing, we can refine our illustration of a database system to appear as shown in Figure 1-7.
Starting from the right of Figure 1-7, the
database
is a collection of related tables and
other structures. The
database management system (DBMS)
is a computer program used
to create, process, and administer the database. The DBMS receives requests encoded in SQL
and translates those requests into actions on the database. The DBMS is a large, complicated
program that is licensed from a software vendor; companies almost never write their own
DBMS programs.
Figure 1-6
the Components
of a Database System
Database
Application
Database
DBMS
Users
• Create
• Process
• Administer
Figure 1-7
the Components of a
Database System
with SQL
S
Q
L
Database
Application
Database
DBMS
Users
• Create
• Process
• Administer
Search WWH ::
Custom Search