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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Database design dilemma - not null vs nullable
OK, I'm not a guru or heavy weight by any means. But my reaction is "That
stinks". NULL is a useful concept. It means "I don't know.". Why should some
"magic value" mean "I don't know"? Now, using a default is OK so long as the
default chosen is reasonable. Like defaulting a timestamp to the current
date & time for a logging application. Or defaulting a "bonus earned" to 0
for a new employee.
You didn't mention validation but I thought that I'd mention that I prefer that data validation, as much as possible, be encoded in the database system itself. That way, I know that it is consistant. And documented in a single place. With all the validation being done in the application, then you must look at each place that the column can be modified to be sure that the validation is correct. If the valid values are changed, then you must find & update every place in every application where that column can be modified and make sure that the proper checks are in place. You must somehow ensure that a programmer doesn't decide not to do the validation because "it just can't be wrong!"
Just my opinion, for whatever it may be worth to you.
All opinions are my own and are not the opinions of my employer.
> -----Original Message-----
> From: Siv Chelakkara [SMTP:Siv.Chelakkara_at_3cc.co.wayne.mi.us]
> Sent: Friday, January 05, 2001 12:21 PM
> To: Multiple recipients of list ORACLE-L
> Subject: Database design dilemma - not null vs nullable
>
> Hi all,
>
> We have an outside vendor developing an application, which we will
> ultimately inherit for maintenance. They are porting this application
> from a different database platform to Oracle, since we are an Oracle shop.
> They have decided to make every column in every table a NOT NULL column.
> They want to implement default values at the database level for every
> column (' ', 0 and some low date for varchar2, number and date) and then
> let the application validate and enforce significant data as required. I
> am looking for opinions on the pros and cons of this type of approach,
> both from a database and application point of view.
>
> Thanks,
>
> Siv
>
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Siv Chelakkara
> INET: Siv.Chelakkara_at_3cc.co.wayne.mi.us
>
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Received on Fri Jan 05 2001 - 13:17:52 CST
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