HP Intelligent Management Center Standard Software Platform - Manual (Page 591)

Changes made to the value of a data parameter require a report refresh to
fetch new data from the database. For example, a report will be refreshed
when a data parameter is used to generate a query.
Non-data parameters are used in:
• Saved data selection formulas
• Conditional formulas
• Parameters placed on the report
Changes made to the value of a non-data parameter will filter the saved data
of the report and will not require a refresh. This process minimizes the
processing demand on the database. For example, a title is a non-data
parameter.
Note:
Non-data parameters change the presentation of existing data. It is best to
use them only in a way that makes sense for the report. For example, do not
filter using a saved data selection formula to display values that are below
100,000 if you have a record selection formula that only selects values above
100,000 from the database. Using selection formulas improperly may provide
confusing results, or even blank pages.
Optional parameters
Crystal Reports supports optional parameters. An optional parameter is a
prompted value that does not have to be supplied by the user.
Report designers should provide some guidance to the end user that a
parameter is optional by adding this information to the prompt text.
Optional parameters are treated by Crystal Reports as optional anywhere
within the report that they are used. You cannot set one instance of the
parameter to optional and another to mandatory.
Note:
• After you set a parameter to optional, if you use the "Select Expert", the
system will automatically add the selection formula for you using the
HasValue()
function.
The "Formula Workshop Editor" does not automatically add the formula.
Only the "Select Expert" automatically adds the formula for you.
Crystal Reports 2008 SP3 User's Guide 591
23 Parameter Fields and Prompts
Parameter and prompt overview