Christopher Browne wrote:
> Jon.Ericson@jpl.nasa.gov (Jon Ericson) writes:
>> Christopher Browne <cbbrowne@acm.org> writes:
>> [an outline of a tutorial]
>>> - Why avoid NULLs?
>>
>> I'm curious about the answer to that question. Is it a relational
>> database theory problem or PostgreSQL implementation issue? Or do
>> you just talk about inappropriate uses of NULL?
>
> It somewhat parallels the infamous "GOTO considered harmful" that
> caused great controversy around the ACM for many years after Dijkstra
> sent in a letter by that title, and yes, it's an issue of "relational
> database theory."
And I still think avoiding GOTO alltogether is a good thing. Instead the
language is supposed to support COMEFROM, which you put at the place
where you want to continue when the program had reached some other
place. You can think of it much like an exception handler, the exception
being that the program survived to a point where you not really expected
it to get to.
Fortunately PostgreSQL has this even down on the per row level in form
of the BEFORE TRIGGER returning NULL and INSTEAD rewrite rules.
Jan
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