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From Peter Donald <dona...@apache.org>
Subject Re: [ANN] Collecting requirements for Ant2
Date Thu, 22 Mar 2001 06:37:35 GMT
At 09:53  21/3/01 -0800, Alex Smith wrote:
>Peter Donald <donaldp@apache.org> wrote:
>
>[re: foreach being evil and SQL's select being good]
>
>>select has zero ordering semantics
>
>Foreach also has zero ordering semantics. In fact, saying 'SELECT * FROM 
>MyTable' is equivalent to 'foreach (*) in MyDirectory'. (In reality both 
>select and foreach impose default ordering on the result set but that still 
>doesn't produce a valid argument against either).

Well where foreach has been implemented it often does have ordering
semantics (as a matter of fact I can't think of a implementation that does
not have ordering semantics - can you?). However very few decent (I can't
think of any) implementations of SQL have ordering semantics at that level
(people who know the underlying strategy/structures/db can force a
particular ordering but that was no inherent in SQL last time I read about
it).

>SELECT * FROM MyTable WHERE (SELECT ...) is roughly equivalent to
>
>foreach $file in MyDirectory
>  foreach $extension in $file
>    print $file.$extension

oh really ? Luckily you have that ketword "roughly" eh? ;)




Cheers,

Pete

*-----------------------------------------------------*
| "Faced with the choice between changing one's mind, |
| and proving that there is no need to do so - almost |
| everyone gets busy on the proof."                   |
|              - John Kenneth Galbraith               |
*-----------------------------------------------------*


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