Re: Extract only maximum date from column

On Thursday, December 4, 2025, Rich Shepard <rshepard(at)appl-ecosys(dot)com>
wrote:

> I want the script to extract only the maximum `next_contact' date and
> haven't learned how to do this from my reading of web sites.
>
> The script:
>
> select p.person_nbr, p.company_nbr, c.next_contact
> from people as p, contacts as c
> where c.next_contact >= '2025-11-01'
> group by p.person_nbr, p.company_nbr, c.next_contact
> order by p.person_nbr, p.company_nbr, max(c.next_contact);
>
> returns all contacts rather than only the latest one.
>
> Is using a sub-select the proper way?
>

I would go with a lateral join subquery of the contracts table. Using an
aggregates to perform ranking is an anti-pattern. You want the contract
ranked first when ordered by contract_date. Either use a window function
to explicitly rank the contracts or use a limit/fetch clause to simply
return the first ordered one.

You also seem to have completely missed joining people to contracts -
suggest using explicit “join” clauses to make that error less likely.

David J.