to further try and explain the NULL issue in crystal here is an example,
(this example assumes you tha you are not using default values for nulls)
isnull(fielda) or fielda=""
will not evaluate the same
fielda="" or isnull(fielda)
the first statement will return "True" for nulls or empty strings and "False" for all other instances.
The second statement will return "True" for empty strings, false for non empty strings and nothing for nulls.
the second statement is evaluating fielda for an empty sting first, since we did not tell it how to handle the a null, it just stops evaluating and never gets to the second condition and does not return any value at all.
You can place these two formula fields side by side on your report to see how they act differently.
If you use the formula editor option setting 'Default values for null' it tells the formual how to handle the null and allows it to continue to check all of the conditions in the formula.
Edited by DBlank - 06 Dec 2012 at 5:56am