How to create formulas based on null values in SAP Crystal Reports

We use ISNULL function in Crystal Report to checks for data within a cell - if a cell contains no data it "ISNULL." The basic syntax for using ISNULL in Crystal Report formulas is as follows:

IF ISNULL({Constituent.LastName}) THEN {Constituent.OrgName} ELSE {Constituent.LastName}

The formula will check the LastName field in the Constituent table, and determine if it is blank. If it contains no data, the formula will display the OrgName field. If there is data in the field, however, the LastName will be displayed.

The same results can also be obtained from the following formula:

IF NOT ISNULL({Constituent.LastName}) THEN {Constituent.LastName} ELSE {Constituent.OrgName}