Re: [SQL] Complicated "group by" question

[Jean-Luc Lachance]

Andrew,

If assing is not a many to many relation,
why did you not fold accept_id into assign?

Any way, here is the query you need:

select assign.reviewer_id, ss.max_assign_date,
  accept.assign_id, accept.accept_id
from (
  select reviewer_id, max( assign_date) as max_assign_date
  from assign group by reviewer_id) as ss, assign, accept
where ss.reviewer_id = assign.reviewer_id
  and ss.max_assign_date = assign.assign_date
  and assign.assign_id = accept.assign_id;

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
                ...             ...

Thanks for any guidance.

Andy

----------------------------------------------------------------------
Andrew J Perrin - http://www.unc.edu/~aperrin
Assistant Professor of Sociology, U of North Carolina, Chapel Hill
[EMAIL PROTECTED] * andrew_perrin (at) unc.edu

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