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Eclipse BIRT Report Developer Guide
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Enabling the User to Filter Data 

When you create a report, you build a data set and typically specify filter criteria to display specific data in the report. When a user views the report, the user sees the information that you selected. As users become familiar with the report and recognize its potential as an analytical tool, they may want to view the data in different ways. For example, in a sales report, a user may want to view only sales in California, or sales over a certain amount, or sales that closed in the last 30 days.

The solution for this type of ad hoc reporting requirement is for the report to prompt the user to provide information that determines what data to display. Report developers make this solution available by using report parameters.

To enable users to filter database data, you complete the following tasks in the recommended order. For detailed information about these tasks, see the corresponding topics later in this section.

Bind the data set parameter to the report parameter, so that the data set parameter gets the user-specified value from the report parameter and passes it to the SQL query.

How to create a basic report parameter

Figure 12-1 New Parameter

Figure 12‑1
In Name, type a name for the parameter. It is good practice to use a prefix, such as RP, in the name to help distinguish report parameters from other parameter types, such as data set parameters. For example, a report parameter used to filter on a quantityinstock field might be named RP_quantityinstock. The value you specify in Name appears as the prompt to the report user if you do not specify a value for the next property, Prompt text. Rather than specify only a Name value for the parameter, you should use a technically descriptive value in Name, and provide a user-friendly value in Prompt text.
The data type that you select does not have to match the data type of the field in the data source. Values in an orderID field, for example, can be stored as integers in the database, but the report parameter that is associated with this field can be of decimal or string type. The data type that you select for the report parameter determines the formatting options that are available if you choose to provide a default value or a list of values for the report parameter.

How to insert a parameter marker in the SQL query

This procedure assumes that you already created a data set.

In Data Explorer, right-click the data set whose query you want to edit, then choose Edit. Edit Data Set displays the query.
Figure 12‑2 shows an example of a query with two parameter markers.

Figure 12-2 Query with two parameter marker

At this point, you are ready to define a data set parameter for each ? parameter marker. The next section describes this task.

How to define a data set parameter

This procedure assumes that you already inserted a parameter marker in the SQL query. If you use multiple data set parameters, create them in the order in which their corresponding parameter markers appear in the WHERE clause.

In Data Explorer, choose the data set for which you want to create parameters. Edit Data Set displays the query for the data set.
Choose Parameters. Edit Data Set displays the Parameters page. This page displays placeholder data set parameters, which BIRT Report Designer creates for each ? parameter marker you specify in the WHERE clause of the query
In Name, type a name for the data set parameter. It is good practice to use a prefix, such as DSP, to differentiate the parameter from other parameter types, such as report parameters.
Figure 12‑3 shows an example of a data set parameter definition where the data set parameter, DSP_quantityinstock, is linked to a report parameter, RP_quantityinstock.

Figure 12-3 Data set parameter definition

Repeat steps 3 and 4 to define additional data set parameters for any other parameter markers that you inserted in your SQL query.
Test the parameters to verify that the query is updated with user-specified values and that the report shows the results you expect.
Enter Parameters displays all the report parameters that you created. Figure 12‑4 shows example report parameters, RP_quantityinstock and RP_productvendor. The parameter names are displayed because values were not supplied for the Prompt text property.

Figure 12-4 Enter Parameters

Figure 12‑4

If you completed all the tasks that were described earlier in this section, the WHERE clause of your query incorporates the specified values, and the report displays the rows that match the WHERE clause.

(c) Copyright Actuate Corporation 2009

  Published under the terms of the Eclipse Public License Version 1.0 ("EPL") Design by Interspire