Re: Lowest 2 items per

Sorry, Mike, previous query was flawed.

This is (hopefully) the correct version

Best,
Oliver
SELECT make, model, color,type, subquery1.cpp, min(cost/yield) as cpp2(SELECT printers.make, printers.model,
consumables.color,consumables.type,min(cost/yield) AS cppFROM printersJOIN printersandconsumables ON printers.printerid
=printersandconsumables.printeridJOINconsumables ON consumables.consumableid =printersandconsumables.consumableidWHERE
consumables.costIs Not NullAND consumables.yield Is Not NullGROUP BY printers.make, printers.model,
consumables.color,consumables.type)subquery1JOIN(SELECT printers.make, printers.model,
consumables.color,consumables.type,cost,yieldFROMprintersJOIN printersandconsumables ON printers.printerid
=printersandconsumables.printeridJOINconsumables ON consumables.consumableid =printersandconsumables.consumableidWHERE
consumables.costIs Not NullAND consumables.yield Is Not Null) subquery2
 
ON (subquery1.make = subquery2.make
AND subquery1.model = subquery2.model
AND subquery1.color = subquery2.color
AND subquery1.type = subquery2.type)WHERE subquery2.cost / subquery2.yield <> subquery1.cppGROUP BY
subquery2.make,subquery2.model, 
 
subquery2.color,subquery2.type,subquery1.cppORDER BY make, model;

----- Original Message ----- 
From: "Oliveiros d'Azevedo Cristina" <oliveiros.cristina@marktest.pt>
To: "Relyea, Mike" <Mike.Relyea@xerox.com>; <pgsql-sql@postgresql.org>
Sent: Friday, June 01, 2012 3:56 PM
Subject: Re: [SQL] Lowest 2 items per


> Hi, Mike,
>
> Can you tell me if this gives what you want, and if it doesn't, what is 
> the error reported, or wrong result ?
>
> This is untested query, so Im not sure about it.
>
> Best,
> Oliver
>
> SELECT make, model, color,type, subquery1.cpp, min(cost/yield) as cpp2
> (
> SELECT printers.make, printers.model, consumables.color,
> consumables.type, min(cost/yield) AS cpp
> FROM printers
> JOIN printersandconsumables ON printers.printerid =
> printersandconsumables.printerid
> JOIN consumables ON consumables.consumableid =
> printersandconsumables.consumableid
> WHERE consumables.cost Is Not Null
> AND consumables.yield Is Not Null
> GROUP BY printers.make, printers.model, consumables.color,
> consumables.type
> ) subquery1
> NATURAL JOIN
> (
> SELECT printers.make, printers.model, consumables.color,
> consumables.type
> FROM printers
> JOIN printersandconsumables ON printers.printerid =
> printersandconsumables.printerid
> JOIN consumables ON consumables.consumableid =
> printersandconsumables.consumableid
> WHERE consumables.cost Is Not Null
> AND consumables.yield Is Not Null
> ) subquery2
> WHERE subquery2.cost / subquery2.yield <> subquery1.cpp
> GROUP BY make, model, color,type
> ORDER BY make, model;
>
>
> ----- Original Message ----- 
> From: "Relyea, Mike" <Mike.Relyea@xerox.com>
> To: <pgsql-sql@postgresql.org>
> Sent: Friday, June 01, 2012 3:34 PM
> Subject: [SQL] Lowest 2 items per
>
>
> I need a little help putting together a query.  I have the tables listed
> below and I need to return the lowest two consumables (ranked by cost
> divided by yield) per printer, per color of consumable, per type of
> consumable.
>
> CREATE TABLE printers
> (
>  printerid serial NOT NULL,
>  make text NOT NULL,
>  model text NOT NULL,
>  CONSTRAINT printers_pkey PRIMARY KEY (make , model ),
>  CONSTRAINT printers_printerid_key UNIQUE (printerid ),
> )
>
> CREATE TABLE consumables
> (
>  consumableid serial NOT NULL,
>  brand text NOT NULL,
>  partnumber text NOT NULL,
>  color text NOT NULL,
>  type text NOT NULL,
>  yield integer,
>  cost double precision,
>  CONSTRAINT consumables_pkey PRIMARY KEY (brand , partnumber ),
>  CONSTRAINT consumables_consumableid_key UNIQUE (consumableid )
> )
>
> CREATE TABLE printersandconsumables
> (
>  printerid integer NOT NULL,
>  consumableid integer NOT NULL,
>  CONSTRAINT printersandconsumables_pkey PRIMARY KEY (printerid ,
> consumableid ),
>  CONSTRAINT printersandconsumables_consumableid_fkey FOREIGN KEY
> (consumableid)
>      REFERENCES consumables (consumableid) MATCH SIMPLE
>      ON UPDATE CASCADE ON DELETE CASCADE,
>  CONSTRAINT printersandconsumables_printerid_fkey FOREIGN KEY
> (printerid)
>      REFERENCES printers (printerid) MATCH SIMPLE
>      ON UPDATE CASCADE ON DELETE CASCADE
> )
>
> I've pulled together this query which gives me the lowest consumable per
> printer per color per type, but I need the lowest two not just the first
> lowest.
>
> SELECT printers.make, printers.model, consumables.color,
> consumables.type, min(cost/yield) AS cpp
> FROM printers
> JOIN printersandconsumables ON printers.printerid =
> printersandconsumables.printerid
> JOIN consumables ON consumables.consumableid =
> printersandconsumables.consumableid
> WHERE consumables.cost Is Not Null
> AND consumables.yield Is Not Null
> GROUP BY printers.make, printers.model, consumables.color,
> consumables.type
> ORDER BY make, model;
>
>
> After doing a google search I didn't come up with anything that I was
> able to use so I'm asking you fine folks!
>
> Mike
>
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