On Jun 30, 2009, at 4:14 AM, Waldemar Bergstreiser wrote:
I don't get it either. by *= do you mean the Oracle-style outer
join?
in which case why is this not just
select * from a,
left outer join b on (a.b_id = b.id)
left outer join c on (b.c_id = c.id)
left outer join d on (a.d_id = d.id)
left outer join f on (d.f_id = f.id)
<snip>
select * from a left outer join b on (a.b_id=b.id) ....
But I don't see any clear way to specify that table C should be
outer joined only if we got a row from table B.
Well that would be the default since if you get no row from b b.c_id
will be null.
and if I have a row in table C where c.id is null? A don't know.
No, it's perfectly clear as 'NULL = NULL' evaluates to false:
postgres=# select null = null;
?column?
----------
(1 row)
Erik Jones, Database Administrator
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