RE: NULL's on the Iseries

["Joe Pluta" <joepluta@xxxxxxxxxxxxxxxxx>]

> From: Raul A. Jager W.
> 
> In my opinion, nulls are better implemented in SQL than in RPG.  When
I
> compare a field in SQL I don't need to wory if it is null, neither in
an
> aritmetic operation.  Nulls compare always false, as they should and
> give null when added to someting else.  In RPG I need check for null
> (%nullind) before using the field.

Personally, I think NULL is just a hardcoded way of handling a standard
business problem.  You could just as easily use a field to check for
NULL, which is in effect what RPG does.

You say that NULL compare "always returns false, as they should".  What
happens when you compare two NULL fields?  I bet you can come up with
situations where you want this to compare as true, and some where you
want it to compare as false.

Or that adding a NULL always results in NULL.  There are plenty of
places where I might want the column to add as zero, not NULL.  So, no,
NULL does not always do what makes sense.  It just does what NULL does,
and that's whatever the NULL implementers thinks it should do.

In fact, what the NULL does is provide a hardcoded shortcut for what is
in effect a database design issue.  It's fine, but often overused.  And
there really need to be high-level capabilities to allow queries to
assign default values to NULLs without having to COALESCE them.  I'm not
against NULL, I'm just saying they're not perfect.

Joe