[Helma-user] allowing NULL VALUES in foreign keys

[Julian Tree]

On Aug 21, 2006, at 6:21 PM, nex wrote:
> Julian Tree wrote:
>> the CTO at the time eventally replaced all the NULL with zero and the
>> system speed up.
> that is possible, but my guess is that he actually also set the column
> NOT NULL; that way i can see how index-related operations became  
> faster.
> but if you leave that bit of information out, it seems  
> unbelievable, so
> i also agree with nighthawk :-)

Thanks for the response. After that incident, I started to create all  
my database column with NOT NULL from scratch, and that is where  
helma is complaining.  Whenever if I don't add a child node to a  
parent, the foregien key is set to null.  This conflict with the NOT  
NULL constrain.  Maybe there should be a way to insert 0, '' instead  
of NULL.

I can understand that alot of applications depends on fields to be  
null, but if I am building my system from scratch, why don't I just  
start off with a system that doesn't allow null values in any  
columns? Disk space is cheap. Now I know there is the theoretical  
different between NULL (unknown value) and (blank a known but blank  
value).  Maybe someone can give me an example, but i don't see any  
difference from an application logic point of view and most  
importantly from a user point of view to have to have null or blank.   
It just seem like one less things to worry about.