From: | Richard Huxton <dev(at)archonet(dot)com> |
---|---|
To: | Michael Avila <Michael(dot)Avila(dot)1(at)sbcglobal(dot)net> |
Cc: | SQL PostgreSQL MailList <pgsql-sql(at)postgresql(dot)org> |
Subject: | Re: Need SQL Help Finding Current Status of members |
Date: | 2005-12-16 09:24:22 |
Message-ID: | 43A287C6.2090501@archonet.com |
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Thread: | |
Lists: | pgsql-sql |
Michael Avila wrote:
> I have a table which keeps track of the status of members. In the table is
>
>
> member_id int(8)
> status_code char(1)
> status_date date
>
> KEY member_id (member_id,status_code,status_date)
>
>
> Each member can have multiple records because a record is added each time
> the status changes but the old record is kept for history.
>
> What I want to do is find the latest status for each member.
Michael Fuhr has already described on solution, but if you can alter the
table definition then there might be a neater solution.
Replace "status_date" with "status_expires" and make it a "timestamp
with time zone". Set the expiry to 'infinity' for the current record and
you then have a simple select to find the most recent.
If you regularly want to find which record was active on a particular
time you'll want two columns: valid_from and valid_to. This makes it
much easier to find a row for a specific date.
--
Richard Huxton
Archonet Ltd
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