On Mon, 2004-01-05 at 20:29, Corey Edwards wrote:
> On Mon, 2004-01-05 at 19:14, Daniel Crookston wrote:
> > Ewww, sub-selects.  Not a very efficient use of the DB, is it?  I was under
> > the impression that it's just as fast (with MySQL at least) to just do the
> > sub-select yourself in the code instead of relying on the database to do it.
> 
> That sounds like a dubious claim to me. I'd be interested in some hard
> numbers to back it up. I can't see how adding network latency, memory
> copies and data transfer can possibly speed up an algorithm. Well I can,
> but this is hardly [EMAIL PROTECTED]
> 
> Fact is sometimes subselects are an appropriate construct and a query
> will benefit from a server which supports them.

More importantly (IMHO) subselects are a more elegant way to express
your query. It's probably true that you can convert almost any subselect
to a left outer join, but that's just not an elegant way to do it, nor
is it intuitive.

BTW: If any subselect can be expressed as a join why can't the DB server
just do that conversion for me?


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