Re: [GENERAL] Apparently I don't understand full outer joins....

[Thomas F . O'Connell]

Your second example is breaking the syntax of from_item ( see 
<http://www.postgresql.org/docs/7.4/static/sql-select.html> ). Your 
join_condition has to be applied to the two from_items associated by 
join_type. I don't think multiple join_conditions can be applied 
sequentially the way you're trying to do it.

You could probably create a nested structure, though.
-tfo
--
Thomas F. O'Connell
Co-Founder, Information Architect
Sitening, LLC
http://www.sitening.com/
110 30th Avenue North, Suite 6
Nashville, TN 37203-6320
615-260-0005
On Jan 25, 2005, at 2:29 PM, Ben wrote:
I run this:
select
        coalesce(a.n,0) as a,
        coalesce(b.n,0) as b,
        coalesce(a.s,b.s) as s
from
        ( select 1 as n, 0 as s) a full outer join
        ( select 2 as n, 1 as s) b
on
        a.s = b.s
... and get this:
a | b | s
---+---+---
 1 | 0 | 0
 0 | 2 | 1
(2 rows)
Perfect! Now, I try to extend my understanding to 3 subselects:
select
        coalesce(a.n,0) as a,
        coalesce(b.n,0) as b,
        coalesce(c.n,0) as c,
        coalesce(a.s,b.s,c.s) as s
from
        ( select 1 as n, 0 as s) a full outer join
        ( select 1 as n, 1 as s) b full outer join
        ( select 2 as n, 2 as s) c
on
        a.s = b.s and
        b.s = c.s
.... and get a syntax error at the end of my query. Apparently what I'm
trying to do doesn't make sense?
Oh, this is on version 7.4, if that makes a difference.
---
Ben Chobot
Senior Technical Specialist, Washington Mutual
206-461-4005

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