Re: Foreign key in Oracle Sql

From: Dieter Nöth <dnoeth_at_gmx.de>
Date: Fri, 21 Jan 2005 19:56:42 +0100
Message-ID: <35d1jgF4lgs7eU1@individual.net>

David Cressey wrote:

> The second is that Oracle warns its users that code that depends on the
> confusion between the empty string and NULL
> might be broken in a future release of Oracle! (emphasis mine). If you
> don't believe me, check out the Oracle documentation.

My 2 Euro cents:
- Oracle is trying to achieve Core SQL:1999 compliance, like any other DBMS vendor: IMHO that's the reason why they added CASE support and ANSI JOIN syntax.
- In SQL:1999 Varchar is a part of Core Level and according to that NULL and '' is different.

- It's impossible to change the implementation of Varchar2 in Oracle.
- Varchar2 isn't a valid datatype in Standard SQL
- The solutions is already mentioned within the manuals:

"The VARCHAR datatype is currently synonymous with the VARCHAR2 datatype. Oracle recommends that you use VARCHAR2 rather than VARCHAR. In the future, VARCHAR might be defined as a separate datatype used for variable-length character strings compared with different comparison semantics."

-> Oracle implements a VARCHAR according to SQL:1999 and leaves Varchar2 the way it is and then the choice is up to the user...

Dieter Received on Fri Jan 21 2005 - 12:56:42 CST