Re: Subquery to select max(date) value
От | David G. Johnston |
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Тема | Re: Subquery to select max(date) value |
Дата | |
Msg-id | CAKFQuwbQ6f9Kqqs-H+js9hi-9c1Q4pWT9pj=Kq9h3Ld2yVCCoA@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: Subquery to select max(date) value (Rich Shepard <rshepard@appl-ecosys.com>) |
Ответы |
Re: Subquery to select max(date) value
|
Список | pgsql-general |
On Thu, Mar 28, 2019 at 3:59 PM Rich Shepard <rshepard@appl-ecosys.com> wrote:
select p.person_id, p.lname, p.fname, p.direct_phone, p.active, o.org_name, sq.*
from people as p
join organizations as o on p.org_id = o.org_id
cross join
lateral
(select a.next_contact
from activities as a
where a.person_id = p.person_id and
p.active='True' and
a.next_contact is not null
order by a.next_contact DESC
limit 1) sq;
It works wellm, but the row order is not that of a.next_contact. In fact,
there seems to be no order in the returned set.
The next_contact column is
in the lateral sub-query. Does this make a difference?
Yes, if you join the result on an ordered subquery to anything you no longer have a guaranteed order for the combined relation.
select ...
from ...
join ...
cross join lateral ...
-- now add an order by for the top-level query
order by
David J.
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