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250 Part Two Information Technology Infrastructure

Microsoft Access has a rudimentary data dictionary capability that displays
information about the name, description, size, type, format, and other properties
of each field in a table (see Figure 6.6). Data dictionaries for large corporate
databases may capture additional information, such as usage, ownership (who
in the organization is responsible for maintaining the data), authorization,
security, and the individuals, business functions, programs, and reports that
use each data element.

Querying and Reporting
DBMS includes tools for accessing and manipulating information in databases.
Most DBMS have a specialized language called a data manipulation language
that is used to add, change, delete, and retrieve the data in the database.
This language contains commands that permit end users and programming
specialists to extract data from the database to satisfy information requests and
develop applications. The most prominent data manipulation language today
is Structured Query Language, or SQL. Figure 6.7 illustrates the SQL query
that would produce the new resultant table in Figure 6.5. You can find out more
about how to perform SQL queries in our Learning Tracks for this chapter.
Users of DBMS for large and midrange computers, such as DB2, Oracle, or
SQL Server, would employ SQL to retrieve information they needed from the
database. Microsoft Access also uses SQL, but it provides its own set of user-
friendly tools for querying databases and for organizing data from databases
into more polished reports.
In Microsoft Access, you will find features that enable users to create queries
by identifying the tables and fields they want and the results, and then select-
ing the rows from the database that meet particular criteria. These actions in
turn are translated into SQL commands. Figure 6.8 illustrates how the same
query as the SQL query to select parts and suppliers would be constructed
using the Microsoft query-building tools.

FIGURE 6.6 ACCESS DATA DICTIONARY FEATURES

Microsoft Access has a rudimentary data dictionary capability that displays information
about the size, format, and other characteristics of each field in a database. Displayed
here is the information maintained in the SUPPLIER table. The small key icon to the left
of Supplier_Number indicates that it is a key field.

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