With the logo issue mentioned above, we can easily create some basic logic that is
driven by Report Parameters to meet these requests. We will look at some examples
in this chapter, and explore this more in depth in the chapter on Scripting.
Data Set Parameters and Report
Parameters
In BIRT, there is a very important distinction between Data Set Parameters and
Report Parameters. This distinction can be confusing at first, which is why I want
to discuss it now. The difference is one of scope and function. A Report Parameter
has a global scope and can be used in a number of different ways in reports. Report
Parameters are user-facing variables that prompt the user for input. If you have ever
worked with traditional reporting language, think of Report Parameters as a global
variable combined with a standard input statement that will fill that variable with
a value.
Data Set Parameters, on the other hand, are limited in scope to within the Data
Set that they are declared in. Data Set Parameters work more like bind variables
in a relational database management system, or a prepared query in a data-aware
programming model, such as ADO or JDBC. Data Set Parameters are typically linked
to Report Parameters to retrieve their values, but that is not always the case. They
can be bound to a number of different sources.
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