Re: [SQL] Complicated "group by" question

[Jeff Boes]

Andrew Perrin wrote:
I have a table of people ("reviewers"), a table of review assignments
("assign"), and a table of review acceptances ("accept"). I would like to
be able to write a query to return the latest (e.g., max(assign_date))
assignment for each reviewer, plus the acc_id field from "accept".  I
think I should be able to do this with a GROUP BY clause, but am having no
luck.
Table structure:
reviewers       assign          accept
-----------------------------------------
reviewer_id     assign_id       accept_id
                reviewer_id     assign_id
...             assign_date
                ...             ...

I think you want to write a non-GROUPed query using "DISTINCT ON". 
Something like this:

SELECT DISTINCT ON (reviewer_id,assign_id)
 reviewer_id,
 assign_id,
 assign_date,
 accept_id
FROM reviewers
JOIN assign USING (reviewer_id)
JOIN accept USING (accept_id)
ORDER BY reviewer_id, assign_id, assign_date DESC;
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________
Jeffery Boes <>< [EMAIL PROTECTED]
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