Re: Union instead of Outer Join

select
item_code, coalesce(user_id, ' ') as user_id
from
item_list l inner join user_detail s on l.user_id
= s.user_id
left outer join user_detail b on l.other_userid =
b.user_id
where
l.item_code = 1234;

Joins can be named in different ways; see the "SELECT"
page in the "SQL Commands" section of the docs.

Your message suggests that you want a right join on b
& l; the syntax above corresponds to what you stated
(per my Oracle reference).

--- Unnikrishnan Menon
<unnikrishnan(dot)menon(at)chennai(dot)transys(dot)net> wrote:
> Hi,
>
> I have this query in oracle which I'am trying to
> port to PostgreSQL :
>
> Select
> item_code, nvl(user_id,' ') as user_id
> from
> item_list L, User_detail B, User_detail S
> where
> L.user_id = S.User_id and
> L.other_userid = B.user_id(+) and
> L.item_code = 1234;
>
> This query gives me 1 row as result. L.other_userid
> could be null.
>
> I try changing the query thus in postgreSQL :
>
> Select
> item_code, nvl(user_id,' ') as user_id
> from
> item_list L, User_detail B, User_detail S
> where
> L.user_id = S.User_id and
> L.other_userid = B.user_id and
> L.item_code = 1234
> Union
> Select
> item_code, nvl(user_id,' ') as user_id
> from
> item_list L, User_detail B, User_detail S
> where
> L.user_id = S.User_id and
> L.item_code = 1234 and
> 0 = ( Select
> count(*)
> from
> listed_items L, user_detail B,
> user_detail S
> where
> L.other_userid = B.user_id);
>
> The above query does not return any row. Where could
> I be going wrong?
>
> Any help would be appreciated.
>
> Thanx in advance
>
> Unni
>

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