[thelist] table join for 4 tables

[Joshua Olson]

> -----Original Message-----
> From: Peter Brunone (EasyListBox.com)
> Sent: Thursday, November 03, 2005 9:44 PM

> As for the well-known fact that implicit inner joins have been
> deprecated, is there any good reason to use that arcane syntax beyond
> "that's what they say we're supposed to use"? I'm genuinely 
> curious; is there a performance gain or other advantage to be had?

This is a most excellent question. And, as it turns out, that there are a
couple good reasons to use the JOIN syntax:

1. More understandable... it's a bit easier to see what's going on. This
is, of course, a subjective point.

2. More flexible... the honest truth is that there are some things you can
specify with the JOIN syntax that aren't even possible with the old syntax.
Please don't ask me to recall from the back of my brain an example, but I'm
100% sure that I ran into a scenario sometime a few years back where the
JOIN syntax was the only thing that made it possible.

3. JOIN ordering... when you start to introduce OUTER JOINs into the
equation, suddenly the ordering of the joins is important. INNER JOINING on
two OUTER JOINED tables is not the same as OUTER JOINING on two INNER JOINED
tables. It's tough to wrap your head around, but it's demonstratable with
some fairly basic examples. This may be, coincidentally, what I was
remembering vaguely in reason number 2. 

I just realized that your question above says "implicit inner joins". To
that I'll comment that I don't suppose there IS any real advantage to using
JOIN syntax since INNER JOINS are fully commutable. But, delve into the
world of OUTER JOINs and the advantage should become apparent.

<><><><><><><><><><>
Joshua L. Olson
WAE Tech Inc.
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