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An old adage states that "A picture paints a thousand words." This adage is certainly evident in many executive information systems. By being able to view database trends graphically, an Oracle database user is better able to make decisions based on this data. Oracle Graphics is used to graphically display database information.

We can run Oracle Graphics to display data charts from the Oracle database; however, this tool is used primarily as a graphical server that can present Oracle data within other compatible applications such as Oracle Forms or Oracle Reports.

The Oracle Graphics Environment

Like Oracle Forms and Oracle Reports, Oracle Graphics is designed to operate in a graphical user interface (GUI) environment such as Microsoft Windows. We can perform functions either by selecting them from a menu or by clicking an iconic button. The Oracle Graphics Designer consists of two primary components i.e, The Object Navigator and The Layout Editor.

The Layout Editor

wpe21.jpg (3476 bytes)The Layout Editor presents a canvas that will contain the charts as they are created. You operate this tool by using iconic buttons and menu picks. You use the buttons along the left side of the Layout Editor window to create and manipulate the chart layout objects.

Colour Platelets & Buttons

Below these iconic buttons there is a square that displays the current visual attribute for the selected item This display indicates the fill color, line color, and text color for the object.

At the top of the Layout Editor window is another series of iconic buttons that are used for module control. The first two buttons open an existing chart and save the current chart. The next button is used to start up the runtime simulator to test the operation of the graphics module, as it would operate in production. The last three buttons are used to cut, copy, and paste layout objects between the display and the Windows clipboard.

Initializing the Graphics Environment

To utilize the features of Oracle Graphics and to ensure compatibility with other tools, Oracle Graphics enables you to initialize the designer environment based on a set of personal preferences. To configure Oracle Graphics, select the Tools Options dialog box by selecting Tools | Tools Options from the menu.

The Oracle Graphics options wpe22.jpg (6399 bytes)are defined in two tabs. The first tab, Defaults, defines the parameters for charts that will be created in the Graphics Designer; the first field defines the copyright message that will appear on the charts. The Date and Number buttons are used to establish format masks for dates and numeric fields in Oracle Graphics.

Creating a New Display

Configure Oracle Graphics to automatically open a new blank display upon startup. However, if you need to create a new display after startup, you can do so by selecting File | New | Display from the Designer menu or using the Ctrl+N hot key. A new blank display will be created in the Object Navigator according to the preferences defined in the Tools Options dialog box.

Defining Displays

A display is the basic modular unit for Oracle Graphics. Within a display, a chart or set of charts comprises the functional module that makes up an Oracle Graphics application unit.

Creating a Pie Chart

wpe23.jpg (2923 bytes)A pie chart presents data from several sources to indicate the portion that each contributes to the total for all sources. Create a new chart in Oracle Graphics using either a one-step or two-step method. To use the one-step method, first click the mouse within the Layout Editor canvas to activate the editor and then select the Chart | Create Chart from the menu. A query dialog box will appear that will enable you to name and create a new query to select data for the pie chart.

Creating a Columnar Chart

wpe24.jpg (2993 bytes)A columnar chart displays related data in a series of vertical filled bars. To create this chart using the two-step method, click the mouse within the Object Navigator and select the Queries category. Using the iconic buttons at the left of the Object Navigator, click the Add Object icon to create a new query.

Other Chart Types

wpe25.jpg (4439 bytes)Oracle Graphics provides the functionality to create ten types of charts, with further subtype delineation, to define a total of 56 different chart formats. Oracle Graphics has variations of the columnar chart for charts that present data that can be grouped in subcategories. Timing Charts (Gantt Charts) can also be drawn.

Line—straight lines connecting the individual data points.

Step—a horizontal line is drawn at the data point and vertical lines connect the individual point values.

Curve—a smooth curve is drawn through the data points.

Defining Parameters for Charts

The charts created earlier in this chapter depend on the query conditions that are defined in the query definition dialog box. Many graphical applications need the user to execute the query based on a variable parameter that is defined at runtime. Depending on the value entered, the chart will be drawn dynamically by changing the data in the chart at runtime, based on the selection criteria entered by the user.

Creating a Drill-Down Chart

A drill-down chart is a multi-chart application in which an individual chart is dependent on another linked chart.

Creating a Multilayer Chart & Properties

wpe26.jpg (4258 bytes)Another type of multi-chart application is operated by presenting a single chart at a time based on user interaction. To do this, you can create charts on separate layers and coordinate them through the use of buttons or other interface elements. Typically, multi-layer charts are used to display different aspects of related data on separate chart layers.

Formatting Charts with Text and Breaks

Oracle Graphics provides several optional functions that you can use to customize a chart. These functions include text objects and mechanisms for customizing the labels on a chart. Additionally, by grouping data in subcategories, the displays can show data from multiple data sets on the same chart.

Customizing the Chart Labels

wpe27.jpg (3967 bytes)Oracle Graphics provides two methods for customizing the axis labels for a chart. One way to define the labels is to use the SQL syntax method for creating a column alias directly in the select statement. The other way you can modify the chart labels is to explicitly define the axis labels.

Advanced Formatting Techniques

Oracle Graphics provides facilities to enhance the application module by using PL/SQL program units. These program units can be used to modify the default processing for a chart as well as to define how data can be displayed or to determine if the data should be included in the chart at all.

A data filter is used to eliminate data retrieved by a query that should not be included in the chart. Sometimes for better performance a query will retrieve all data from a table without restricting the retrieval in the where clause.