[dba-SQLServer] ANSI null compliance

No don't start that zeroth column argument here, Arthur.  It's been beat
to death in the D List.

Charlotte Foust


-----Original Message-----
From: Arthur Fuller [mailto:artful at rogers.com] 
Sent: Sunday, May 08, 2005 3:18 PM
To: dba-sqlserver at databaseadvisors.com
Subject: Re: [dba-SQLServer] ANSI null compliance


Frankly, I'm not up to chapter on verse on SQL 92, although I read it 
religiously :)

My knee-jerk reaction would be that all columns of whatever type should 
default to NOT NULL, because IMO, Null columns represent a weakness in 
our design model. I hate Null columns, unless the client can express a 
clearly articulated set of circumstances in which said column should be 
null. For example, we hire a new employee and are not sure sure in which

department to place her. Given this objection, I would say, why hire her

then? Client could answer, Because her qualifications are so good we 
don't want her to go elsewhere, we'll find a place for her.

Now JWC would slide into his zero'th column argument here, which I 
flatly reject, but that's another topic.

I think all column declarations should default to NOT NULL and force you

to do extra work to make them nullable. As I see it, if you can do 
without the data, then do without it. Conversely, if you need the data 
then demand it.

Just my $.02.

Susan Harkins wrote:

>Well, here's the problem in a nutshell -- the default isn't in 
>compliance with SQL-92, which is Okay. However, Query Analyzer IS -- 
>which would tend to lead one astray. Does anyone know if Enterprise 
>Manager is too because even though the Pubs default returns 0, in EM, 
>if I create a new table/column, it automatically checks Allow Nulls -- 
>which is the opposite of what you'd expect considering the inner 
>non-compliance. But, my thinking is -- if Query Analyzer is in 
>compliance, perhaps EM is too.
>
>Or else I'm just terribly baffled by the entire exchange.
>
>Susan H.
>
>The Rules from the ANSI-92 standard:
><quote>
>Every column has a nullability characteristic of known not nullable
>         or possibly nullable, defined as follows:
>
>         A column has a nullability characteristic that indicates
whether
>         any attempt to store a null value into that column will
inevitably
>         raise an exception, or whether any attempt to retrieve a value
>         from that column can ever result in a null value. A column C
with
>         <column name> CN of a base table T has a nullability 
>characteristic that is known
>
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