Horton

Re: Basic SQL join question

Michael Meskes <meskes@postgresql.org>

View thread View on postgr.es
From: Michael Meskes <meskes@postgresql.org>
To: Jean-Christian Imbeault <jc@mega-bucks.co.jp>
Cc: PostgreSQL-general <pgsql-general@postgreSQL.org>
Date: 2003-01-31T07:00:11Z
Lists: pgsql-general 
On Fri, Jan 31, 2003 at 12:08:24PM +0900, Jean-Christian Imbeault wrote:
> For example
> ...
> What is the proper SQL to return:
> 
>   a |  b |  c
> ---------------
>  a1   b1   c1
>  a2   b2   c2
>  a3        c3
>            c4

None. Even in theory this is not possible. How shall the database system
know that a1,b1,c1 belong together? You said the tables have absolutely
nothing in common. Keep in mind that SQL works on sets, not on single
values.

Michael
-- 
Michael Meskes
Email: Michael@Fam-Meskes.De
ICQ: 179140304
Go SF 49ers! Go Rhein Fire! Use Debian GNU/Linux! Use PostgreSQL!