Re: Subquery to select max(date) value

[Rich Shepard]

On Thu, 28 Mar 2019, David G. Johnston wrote:

Yes, if you join the result on an ordered subquery to anything you no
longer have a guaranteed order for the combined relation.

David,

This makes sense to me.

select ...
from ...
join ...
cross join lateral ...
-- now add an order by for the top-level query
order by

Tried this and did not do it correctly. Should there be two 'order by', one
in the sub-query, the other in the top-level query? This does not return the
desired order:

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
         order by sq.next_contact DESC;

Obviously, I'm still missing the implementation of your response.

Best regards,

Rich