Subject Re: [firebird-support] Re: Computed Column
Author Martijn Tonies
Hi Werner,

> Please keep in mind that I am not a techie.
> 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).

The one thing to understand, is that NULL is a state, never a value.

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