Re: Complex sql, limit-for-each group by, arrays, updates

From: David Johnston <polobo(at)yahoo(dot)com>
To: pgsql-general(at)postgresql(dot)org
Subject: Re: Complex sql, limit-for-each group by, arrays, updates
Date: 2013-11-27 16:38:04
Message-ID: 1385570284066-5780599.post@n5.nabble.com
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Dorian Hoxha wrote
> Hi,
>
> So i have (table where data will be read) :
> CREATE TABLE data (vid,cid,pid,number);
>
> Tables where data will be writen/updated:
>
> CREATE TABLE pid_top_vids (pid, vid[])
> CREATE TABLE pid_top_cids (pid, cid[])
> CREATE TABLE cid_top_vids (cid, vid[])
>
> I need to , possibly in 1 query, this will run once in a while:
> Get top(10) vids , sorted by 'number',grouped by pid and update the row in
> TABLE(pid_top_vids).
>
> Get top(10) vids, sorted by 'number', grouped by cid and update the row in
> TABLE(cid_top_vids).
>
> Get top(10) cids, sorted by 'number', where number is the SUM() of each
> vid
> GROUP_BY(cid) and update the row in TABLE (cid_top_vids);
>
> So, get data, create sorted array, and update the rows (they exist, so
> only
> the arrays have to be updated).
>
> Possible ?
> Thanks

I would not bother trying to do it in a single SQL statement but each query
is possible, and fairly basic, using UPDATE with a FROM clause containing
the desired sub-query.

David J.

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