How are you handling ASCII 0 values

Question

Hi,
I have noticed a strange thing with ASCII 0 values. in the process of database replication MSSQL to Oracle some columns in the source DB (MSSQL) have some of the values as ascii 0.
when i load this data with sqlldr in oracle and query the table this columns are not considered as null.
ex:
table_name : PriceItems
Column_name : Description
if i query the table with select count() from PriceItems where Description is null* the result is 0
if i query the table with select count() from PriceItems where Description = chr(0)* the result is 301 (actual rows)
how can we handle this kind of situations?
is this a bug of Oracle?
My Oracle Version:
Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64bit Production
PL/SQL Release 11.1.0.7.0 - Production
"CORE     11.1.0.7.0     Production"
TNS for Linux: Version 11.1.0.7.0 - Production
NLSRTL Version 11.1.0.7.0 - Production
Edited by: user8999602 on Sep 3, 2012 9:22 AM

Answer 1

Ascii character zero indicates a NULL character. Not a null string.
A null string is a string without a value - i.e. a string that has no ASCII (or EBCDIC or Unicode) characters. Oracle does not discriminate between Ascii characters.
Character zero is used, on Windows for example, as string terminator. An empty string can thus only contain a zero terminator. And thus the confusion. An empty string is not the same as a null string in this case - but a zero string length implies the string is empty, does not contain characters (despite containing a char zero), and is therefore null.
The issue is inconsistencies in implementation and terminology. NULL itself is a very abused concept in software engineering.