RE: Counterquestion - is Oracle a He or a She - or an It or a hermaphrodite
- From: "Kennedy, Jim" <jim_kennedy@xxxxxxxxxx>
- To: <psinger1@xxxxxxxxxxxxx>
- Date: Fri, 5 Aug 2005 16:48:41 -0700
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Phil Singer
Sent: Friday, August 05, 2005 3:17 PM
Cc: oracle-l@xxxxxxxxxxxxx
Subject: Re: Counterquestion - is Oracle a He or a She - or an It or a
hermaphrodite
rjsearle@xxxxxxxxx wrote:
> On 8/2/05, Billy Verreynne (JW) <VerreyB@xxxxxxxxxxxx> wrote:
>
>
[snip]
> An empty string is not the same as a number that is equal to zero.
>
[snip]
>
>>I don't know a better way to explain it than that.
>>
>>Well Mark, I in turn cannot understand why people do not seem to grasp
>>the very fundemental concept of what a null is and what a value is. I
>>do agree that dealing with NULLs in Oracle using state operators is
>>not ideal as its easier to deal with NULLs using math operators (and
>>in most other languages). But I do not agree with the misconception
>>that an empty string is somehow different from a NULL string.
>
If we can spare the ramblings of someone who once studied analytic
philosophy:
A NULL qua Relational Databases: Missing data, all attributes unknown,
could be anything. Therefore,in this sense , a NULL string cannot be
the same as an empty string. An empty string has zero length, while a
NULL string could have any length (if we only knew).
A NULL, qua 3GL Programming usage: Big Nothing. Any attributes as
empty as possible. Here, NULL and empty do seem synonymous.
Similar to the confusion when calling PL/SQL from SQL where the PL/SQL
has PL/SQL data types defined in terms of SQL data types.
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I explain NULLS in the following manner.
Imagine a medical application where your medical data is stored in a
database. Imagine that your Dr. has never asked you if you have
allergies or not. Further imagine that you become unconcouse and go to
the emergency room. The Dr. in the emergency room looks at your
electronic medical data. Given the information in your electronic chart
what should the Dr. assume about your allergic reactions?:
A. You are Alergic to something.
B. You are not allergic to anything.
C. It is unknown if you are or are not allergic to anything.
The Dr. should assume C. You have not been asked the question so the
data in that column is NULL and the Dr. should make NO assumptions about
your medical condition visa vis allergys. In medicine even if they
asked you the question "Are you allergic to anything?" and you answered
"No" the correct value to store is NKA - No Known Allergies. After
this explanation most people understand what a NULL is.
Jim
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