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Re: update with from

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On Monday, January 23, 2012 10:11:00 pm Sim Zacks wrote:
> On 01/23/2012 07:10 PM, Adrian Klaver wrote:
> > On Monday, January 23, 2012 7:32:35 am Sim Zacks wrote:
> >> On 01/23/2012 05:13 PM, Adrian Klaver wrote:
> >> 
> >> 
> >> When I throw in code to make the select only return the correct rows
> >> The select statement takes 9 secs by itself:
> >> select a.partid,a.deliverywks
> >> from poparts a where popartid in (
> >> 
> >> 	select b.popartid from poparts b
> >> 	join pos c using(poid)
> >> 	join stock.lastrfqdateperpart d using(partid)
> >> 	where c.isrfq and c.issuedate > d.issuedate-7
> >> 	AND b.unitprice > 0::numeric AND b.quantity >= 100::numeric AND
> >> 
> >> c.postatusid = ANY (ARRAY[40, 41])
> >> 
> >> 	and b.partid=a.partid
> >> 	order by b.partid,b.unitprice, b.deliverywks
> >> 	limit 1
> >> 
> >> )
> > 
> > To clarify what I posted earlier, my suggestion was based on rewriting
> > the
> > 
> > second query as:
> >         select b.partid,b.deliverywks b.popartid from poparts b
> >         join pos c using(poid)
> >         join stock.lastrfqdateperpart d using(partid)
> >         where c.isrfq and c.issuedate > d.issuedate-7
> >         AND b.unitprice > 0::numeric AND b.quantity >= 100::numeric AND
> > 
> > c.postatusid = ANY (ARRAY[40, 41])
> > 
> >         order by b.partid,b.unitprice, b.deliverywks
> >         limit 1
> > 
> > I may be missing the intent of your original query, but I think the above
> > gets to the same result without the IN.
> 
> My first query returns all rows of each part ordered such so that the
> row I want to actually update the table with is last. This query returns
> 12000 rows, for the 600 parts I want to update.
> 
> My second query with the limit within the subselect gets 1 row per part.
> This returns 600 rows, 1 row for each part I want to update.
> 
> Your suggestion would only return one row.

Oops. So per a previous suggestion:

select DISTINCT ON (b.partid) b.partid, b.deliverywks from poparts b
        join pos c using(poid)
        join stock.lastrfqdateperpart d using(partid)
        where c.isrfq and c.issuedate > d.issuedate-7
        AND b.unitprice > 0::numeric AND b.quantity >= 100::numeric AND
c.postatusid = ANY (ARRAY[40, 41])
        order by b.partid,b.unitprice, b.deliverywks
      

> 
> See
> http://www.pgsql.cz/index.php/PostgreSQL_SQL_Tricks#Select_first_n_rows_fro
> m_group for reference.

-- 
Adrian Klaver
adrian.klaver@xxxxxxxxx

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