Wojciech Skrzynecki wrote:
> Hello
>
> What component in DB I have to install to use ">= CHR(0)" instead of
> "is not null" .
>

Set the compatibility to 7.0

This is a lloooonnnnngggggg standing point with Oracle: The empty
string is used to represent a NULL.  Which introduces a problem: the
predicate

   (1)  COL1 = NULL

is supposed to be malformed and illegal. Of course, it is easy for the
syntax checker to detect the above, but what about the following:

    (2)  COL = ''  (where I have written two single quotes with no
space in between them).

This construction is a back door into the sort of syntax which is
supposed to be illegal, and which Oracle generally does not allow.
Instead, it will treat expressions like '' as if one had coded NULL
instead, and evaluate them accordingly. And, no matter how hard you try
to store an empty string in a VARCHAR2 column, it will be treated and
handled as if you had stored a null instead. (including CHR(0)).

Now, back in release 6.x and 7.0, this was not enforced so strictly, and
expressions like (1) _could_ be used. I remember bringing in the latest
release of Oracle to my shop (7.1.34), then taking a new job 8 months
later at a 7.0.9 shop, and finding expressions like (1) all over the
place. I was mystified as to why they worked. My boss was mystified as
to why they started failing when we upgraded to 7.1...

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