The beauty of DCPs is that they give you the ability to link prompts together so that each successive parameter’s list of values is determined by the selection in the previous parameter. The value chosen for one parameter is used to filter the data in the next parameter. Thus, each prompt’s selection “cascades” down to the next prompt.

DCPs are used when the list of values is so large that it would be overwhelming for the user to select from. For example, if the user needs to specify which city to filter on, then this list would be enormous if you are selecting from every possible city in the country. However, you can use cascading prompts to ask the user to first select which state they want and then only select the cities within that state. Cascading prompts effectively let you take a large list of values and significantly decrease its size by asking the user preliminary questions to filter out the non-necessary values. Cascading prompts also give your reports a performance boost because there is less load on the database server as the list of values gets filtered down with each parameter.

The benefits of dynamic cascading prompts are as follows:

• Reduces report maintenance because the list of values is always current.
• Simplifies the user interface because the list of values is more manageable.
• Report file size is smaller because the list of values isn’t stored internally.
• Users make better decisions because they get an exact view of their information.
• Improves report performance by querying the database for smaller resultsets.

Dynamic cascading prompts also have limitations. They are as follows:

• Crystal Reports Standard edition can’t create DCPs. This version can use them to prompt the user properly, but you as the report designer can’t use it to create DCPs in a report.
• Cascading prompts must be dynamic. Static prompts can’t be used.

Since dynamic prompts are connected to the database, the database server will be queried every time the parameters are refreshed. If a list of values is small and doesn’t change frequently, you might be better off creating static parameters so that there isn’t unnecessary usage of the database server.

DCPs are backwards compatible with Crystal Reports 10, but only partially. Crystal Reports 10 can open an XI report that has DCPs, but it won’t be able to display the list of values to the user. The user can manually enter parameter values and the report will use them. But the dynamic connection to the database won’t be enabled.