Order within group by?

Question

In my system, I have clients. Clients have programs. I want to display a list of clients, showing their most recent active (if it exists) program.

Thus, we have some

Answer 1

SELECT  c.*, p.*
FROM    clients AS c
JOIN    programs AS p
ON      p.id = 
        (
        SELECT  pi.id
        FROM    programs AS pi
        WHERE   pi.client_id = c.id
        ORDER BY
                pi.close_date=0 DESC, pi.close_date DESC
        LIMIT 1
        )

Thanx should go to @Quassnoi. See his answer in a similar (but more complicated) question: mysql-group-by-to-display-latest-result

---

If you update the programs table and set close_date for all records that it is zero to close_date='9999-12-31', then your ORDER BY will be simpler (and the whole query faster with proper indexes):

        ORDER BY
                pi.close_date DESC

Answer 2

Try this order by clause ...

ORDER BY client.id, CASE WHEN program.close_date = 0 THEN 0 ELSE 1 END, program.close_date DESC