Re: more information on JOINs

From: "postgresql" <pgsql(at)symcom(dot)com>
To: "Francesco Casadei" <f_casadei(at)libero(dot)it>, "PgSQL-SQL" <pgsql-sql(at)postgresql(dot)org>
Subject: Re: more information on JOINs
Date: 2001-09-22 16:00:02
Message-ID: 200109221553.f8MFrMe70541@postgresql.org
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Thanks for this reference, I have been here. I guess my problem is
that I don't understand a need for a 'join' that is returning NULLs. If I
understand <left> <right> <outer> JOINs correctly, they are returning
columns that contain NULLs.

An example please where I would want this result. I have created a
job tracking system that includes invoicing, collections reporting,
aging. When I first learned to do the INNER JOIN ON, I replaced the
processing that I was doing in my client app and let Postgres do it.
So now I am examining and studying the other joins. I just can not
figure out why I would EVER want one. Which leads me to think that I
just don't understand them.

Please, if someone has a good example......

Ted
tedpet(at)symcom(dot)com

-----Original Message-----
From: Francesco Casadei <f_casadei(at)libero(dot)it>
To: postgresql <pgsql(at)symcom(dot)com>
Date: Sat, 22 Sep 2001 17:40:57 +0200
Subject: Re: [SQL] more information on JOINs

> On Sat, Sep 22, 2001 at 08:11:03AM -0400, postgresql wrote:
> > Where can I get more information and examples on using
JOINs. I
> > have been reading over the Chapter 2 on from the interactive
user
> > docs but I need a little more in the way of examples. I am having
a
> > problem understanding when I would need a LEFT or RIGHT
JOIN.
> >
> > Please, a 'point' in the right (no pun intended) direction would be
> > appreciated.
> >
> > Ted
> >
> >
> >
> > ---------------------------(end of
> broadcast)---------------------------
> > TIP 6: Have you searched our list archives?
> >
> > http://archives.postgresql.org
> >
> > end of the original message
>
> Take a look at the reference manual, part I "SQL Commands":
>
>
http://www.ca.postgresql.org/users-lounge/docs/7.1/reference/sql-s
elect
> .html
>
> Francesco Casadei

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