About data filtering
A data set often provides more information than your report needs. You can select specific data rows to use in a report by using a filter. For example, rather than list all customer sales, you can create a filter to select only the sales data for a particular week or only the sales data for a particular region.
Filtering data helps you work effectively with large amounts of data. It enables you to find the necessary pieces of information to answer specific business questions, such as which sales representatives generated the top ten sales accounts, which products generated the highest profit in the last quarter, which customers have not made a purchase in the past 90 days, and so on.
Filtering data can also have a positive effect on processing speed. Limiting the number of data rows used in the report can reduce measurably the load on the database server, because it does not need to return all the rows every time the report is run.
BIRT Studio supports the use of static filters and dynamic filters. You can use a static filter to define a specific filter condition during report design. The data displayed in the report depends on the filter condition specified in the report design. You use a dynamic filter to prompt a user to specify values for which BIRT Studio displays data, when they run the report. The data that appears in the report depends on the values the user specifies when running the report.
When you use filters in a report design, BIRT Studio typically evaluates the filter condition against the rows of data previewed in the report design, 50 rows by default. Increase this number to 200 rows, when creating filters in a report design. If you use the default value of 50 data rows to test a filter condition, BIRT Studio might frequently not be able to return any data that matches the filter you define. Also run the report in BIRT Viewer to view the actual data, and verify that the result is what you expect.

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