RE: SQL table joins: Join vs. Where

[Vern Hamberg <vhamberg@xxxxxxxxxxxxxxxxxxxxxxxxx>]

Joe

I understand your frustration with the black-box nature of this beast. But 
there are places to get some info - the Performance and Optimization manual 
for recent releases has a lot of stuff, including recommendations. Perhaps 
not the detail some of us would like, but a start. The site 
www.iseries.ibm.com/db2 has links to a number of items that can help.

Also, every RDBMS (no quibbling, please, on whether we have one!) takes a 
slightly different tack on a few things. An obvious one is whether to use 
semi-colons to terminate statements. Some interpret BETWEEN in an inclusive 
manner, others in an exclusive manner. These might not be specified in the 
standards. A writer named Joe Celko speaks of these things from time. He 
has an understanding of several of the SQL implementations. One book of his 
is "SQL for Smarties". I recommend it even for iSeries folks.

HTH
Vern

At 09:45 AM 8/12/2004, you wrote:
> > From: CWilt@xxxxxxxxxxxx
> >
> > Do you mean that the following:
> >
> > select A.A1, B.B1
> > from A inner join B
> >    on A.K1 = B.K1
> >
> > will be faster than
> >
> > select A.A1, B.B1
> > from A, B
> > where A.K1 = B.K1
> >
> >
> > I'd like to know where you got that information, because as I
> understand
> > it that is simply not the case.  Both queries would be run exactly the
> > same way.
>
> This is the part I love.  There is no definitive answer, no place to go
> to find these things.  Hopefully we'll solve that with the new website.
> Here's another one I found:
>
> WHERE MYNAME BETWEEN 'LAVERNE' AND 'SHIRLEY'
>
> >From what I've read, in some databases, this will include records where
> MYNAME is LAVERNE, but not SHIRLEY, whereas some databases will include
> both and some will include neither:
> http://www.w3schools.com/sql/sql_between.asp.
>
> Hopefully there's something about this in the ISO SQL99 standard, but
> I'm not up to ponying up $90 to download five PDF files (or $530 for the
> printed versions!).
>
> Joe