Problem when trying to formulate an IIF IsNull statement to test for NULL

Symptom

IIF and IsNull are functions in Crystal Reports that are used in formulas to test fields for blanks, empty strings, missing values and NULL, then return some valid output. This is especially helpful when preparing a report, since these values can cause blank lines to be printed.

For example, you can use the IIF in conjunction with IsNull to detect if a field is NULL, then depending on the binary results (True or False), the formula will set one of two specified parameters for the value. That formula would look something like this:

IIF(IsNull({~CRPT_TMP0001_ttx.install_date}),"TBD","In Progress")


The formula will check the value in the install_date field. If the field is NULL, then TBD (To Be Determined) will be put in the report where the formula has been placed. If the field is a value greater than the empty string, then In Progress will be put there. This is a method for using Crystal Reports to dynamically add information to a report based on criteria set in a formula.