Is This the varchar2 ZLS Issue?

Oracle server Version 8.1.7.4.0 .

According to some googling I've done, there is an issue with respect to zero length strings and varchar2. I suspect the following differences in a select count(*) are caused by it. Can someone simply confirm for me with a yes/no? THe column that contains nulls (not my design) in the where clause below is wo_acct_no.

Thanks very much in advance and if you have any suggestions on how to deal with it, I'd very much appreciated it, thank you.

SQL> edit
Wrote file afiedt.buf

   1 select count(*)
   2 from f_workorder
   3 where
   4 wo_request_date>=to_date('01-MAR-2006')    5* and nvl(wo_acct_no,'none') = 'none' SQL> /    COUNT(*)

        693

SQL> edit
Wrote file afiedt.buf

   1 select count(*)
   2 from f_workorder
   3 where
   4 wo_request_date>=to_date('01-MAR-2006')    5* and nvl(wo_acct_no,'') = ''
SQL> /    COUNT(*)

          0

-- 
Tim   http://www.ucs.mun.ca/~tmarshal/
^o<
/#) "Burp-beep, burp-beep, burp-beep?" - Quaker Jake
/^^ "What's UP, Dittoooooo?" - Ditto