Date: Sun, 25 May 2008 21:03:25 GMT
It does, I gave one, ie., apply, ie., distribute algebraically, the union to the base relations in the view expression, then apply whatever constraints the definition has. Works just as consistently for deletes to joins.
If it just
> guesses at the intent, 50% of the time it will guess wrong, and you'll end
> up with garbage in the database. As a consequence, queries like, "How many
> suppliers are west of the Mississippi?" will return the wrong answer.
My whole point is that the dbms has no business guessing, just following orders. Why anybody would imagine a dumb pre-programmed logical machine can know human intentions can only be pathological mysticism. As they say, "don't believe everything you think".
> But again, it should not allow the update if it has to guess, because
> inevitably, it will guess wrong at least some of the time and the database
> will end up corrupt. That it has to guess is not a guess.
It is mysticism to think that a dbms that follows its own consistent rules is somehow guessing. Received on Sun May 25 2008 - 23:03:25 CEST