Subject | Re: [firebird-support] Re: Computed Column |
---|---|
Author | Martijn Tonies |
Post date | 2003-08-25T14:14:41Z |
Hi Werner,
A column can have two states: NULL and NOT NULL.
NULL means "unknown" - no value entered/available.
So in your case:
"unknown" - 4 = ??? ... Indeed: unknown.
If you never should have an "unknown" in your records, DEFAULT 0
could work, depending on your application etc etc...
With regards,
Martijn Tonies
Database Workbench - the developer tool for InterBase & Firebird
Upscene Productions
http://www.upscene.com
> Please keep in mind that I am not a techie.The one thing to understand, is that NULL is a state, never a value.
>
> What is the correct (if there is such a thing) way to define my columns?
>
> Or put another way, is there anything which might bite me later on if I
> define default of Zero for the base columns (F1 and F2 in this case)?
> Especially as I can't think of a case where I care to know that the
> columns are not initialized/set (i.e. Null).
A column can have two states: NULL and NOT NULL.
NULL means "unknown" - no value entered/available.
So in your case:
"unknown" - 4 = ??? ... Indeed: unknown.
If you never should have an "unknown" in your records, DEFAULT 0
could work, depending on your application etc etc...
With regards,
Martijn Tonies
Database Workbench - the developer tool for InterBase & Firebird
Upscene Productions
http://www.upscene.com