Re: WHERE vs. ON

[Perrin Harkins]

On Tue, Feb 3, 2009 at 12:24 PM, Jerry Schwartz
<jschwartz@stripped> wrote:
> Somebody, I think it was somebody from MySQL, said that you should never put
> anything into a WHERE clause that could be put into the ON clause of a JOIN.
> My guess is that this helps with the optimization, but it seems
> counter-intuitive to me.

It seems like it shouldn't make any difference if the optimizer is
smart enough, but in my experience it sometimes does.  Because of
that, I always try to put conditions in the ON clauses when I can,
even if they are not about joining the tables.

- Perrin