OVERVIEW OF MAJOR COMPONENTS - Database Design and Development: An Essential Guide for IT Professionals - page 61

of data or data field. Blocks and items on the form are the places where data is input
or displayed.
Relationship. Represents the associations between separate blocks and items.
Presents all the elements that may be combined to create a small application with
forms.
Editor. Window for viewing and maintaining large data structures.
Lists of values. List of permissible values for individual fields.
Parameters. Used to pass values from form to form.
Property sheets. Contain the characteristics of individual data elements on the
form.
Layout editor. Enables form objects to be laid out on a canvas to create the format
of a form.
Report Writer
In earlier file-oriented data systems, reports were the only means of providing
information to users. Also, all batch processing and printing of reports happened
overnight. In today's database environment, most data retrieval and data manipu-
lation occur on-line in an interactive manner. As we have seen, the query proces-
sor and forms generator components provide online facilities for data access. So,
what is the need for report writers?
Although most information access is on-line, a good deal of information deliv-
ery still remains in the medium of printed reports. Reports may first be viewed on-
line before selecting and printing only the ones needed on hard copy. Nevertheless,
these are reports, and the use of reports is not likely to be eliminated altogether.
Power users and specialized users have needs to format and generate their own
reports. All applications generally include a substantial suite of daily, weekly, and
monthly reports. You can create reports to show detailed and summary data.
Reports can show results of complex calculations; they can print multilevel totals.
Figure 2-12 illustrates design and execution of reports. Note how the report writer
interfaces with the query processor to retrieve the necessary data. After the query
processor delivers the requested data, the report writer formats and prints the
report.
Here are a few significant capabilities of report writers in modern DBMSs:
• Easy interface with query processor to retrieve data based on complicated
retrieval conditions
• Sophisticated layout editors to format intricate reports
• Methods for storing individual report preferences
• Quick construction of tabular reports
• Creation of summary and detailed reports