Another option for selecting ALL in a parameter

Saturday 23 March 2019 @ 11:04 am

I wrote last fall about selecting “ALL” with a string parameter field. My comments at the end list options for making the technique work for numbers and dates. Recently I received a note from one of my colleagues on a better approach, using optional parameters.

Starting with CR 2008 (v14) Crystal has allowed us to define a parameter as “optional”. This allows the user to not enter a value at all in a parameter. However, when you use an optional parameter in a formula you always have to test for the existence of a value in the parameter field before you use. The test often looks like this:

if HasValue ( {?Tax Rate} )
then {Orders.Order Amount}*{?Tax Rate}
else 0

This way the report knows what to do when the parameter is skipped.

Another way of creating an ALL option is to tell the report that any time there is no value entered in the parameter, the user wants ALL values. The formula would look something like this:
(not HasValue ( {?State} ) or {Customer.State} = {?State})

Note that the HasValue() test has to come before any other test that uses that parameter. If you reverse the two tests in this formula it will generate an error whenever you don’t fill in the parameter.

And thanks to Luc Rascar, a Crystal Reports/Business Objects consultant in France, for pointing this out.

(For examples of my most popular formulas, please visit the FORMULAS page on my website.)







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