Null vs. zero length field

[Bob_Lantz_(Guest)]

I was recently looking at some MS Access data with R&R V12 and was trying to get it to give me a list of all records where a certain character field was empty, or it seemed that way. I used the ISNULL calculated function and it didn^t detect any. Looking at the same data I used the LEN function to have it give me those with a zero length and it produced the desired list of empty records.____When you click on the Help button in the calculated field area and pull up the alphabetical list of R&R functions and select "LEN" it says that "Length of a null string is zero." Wouldn^t the correlary be true also, that a string with a zero length is null?____What would cause these two functions to not work the same and zero length to not also be null?

[kfleming]

A null character field is different than a character field that is empty. The ISNULL() function is only true for fields whose value is explicitly set in your table as a NULL value rather than a zero length string. The LEN function does let you use null strings as well as empty strings but an empty field is not the same as a null.____Kathleen__R&R Support____