Strip unwanted commas from text object if value is null

[mpunhani]

I am new to Crystal Reports. I am using version 8 against DB2 database. I have a text object that displays 3 different fields from the database. The values are seperated by commas.
field1, filed2, filed3
If the values are null I do not want to display hanging commas. Is there a formula I can use to not display the comma if the next field value is null?

 

[lbass]

In the text box, place the following:

{field1} {@formula1} {field2} {@formula2} {field3}

...where {@formula1} is:

if not isnull({field2}) then ", " else ""

...and {@formula2} is:

if not isnull({field3}) then ", " else ""

-LB