Re: PostgreSQL Certification

Christopher Browne wrote:
> Jon.Ericson@jpl.nasa.gov (Jon Ericson) writes:
>> Christopher Browne  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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