Skip site navigation (1) Skip section navigation (2)

Re: Lowest 2 items per

From: "Relyea, Mike" <Mike(dot)Relyea(at)xerox(dot)com>
To: Oliveiros d'Azevedo Cristina <oliveiros(dot)cristina(at)marktest(dot)pt>
Cc: <pgsql-sql(at)postgresql(dot)org>
Subject: Re: Lowest 2 items per
Date: 2012-06-01 16:17:50
Message-ID: AF7D9319B29A0242A33C3BF843BD31330EFB8D8D@USA7061MS03.na.xerox.net (view raw or flat)
Thread:
Lists: pgsql-sql
> -----Original Message-----
> From: Oliveiros d'Azevedo Cristina
[mailto:oliveiros(dot)cristina(at)marktest(dot)pt]
> Sent: Friday, June 01, 2012 11:21 AM
> To: Oliveiros d'Azevedo Cristina; Relyea, Mike;
pgsql-sql(at)postgresql(dot)org
> Subject: Re: [SQL] 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 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
>  JOIN
>  (
>  SELECT printers.make, printers.model, consumables.color,
> consumables.type,cost,yield  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
> 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.cpp  GROUP BY
> subquery2.make,subquery2. model,
> subquery2.color,subquery2.type,subquery1.cpp
>  ORDER BY make, model;
> 

Oliver,

I had to make a few grammatical corrections on your query to get it to
run, but once I did it gave me almost correct results.  It leaves out
all of the printer models that only have one consumable with a cost.
Some printers might have more than two black inks and some might have
only one.  Your query only returns those printers that have two or more.

Here's your query with the corrections I had to make
SELECT subquery2.Make, subquery2.Model, subquery2.Color,subquery2.Type,
subquery1.cpp, min(Cost/Yield) as cpp2  
FROM(  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
 JOIN
 (
 SELECT Printers.Make, Printers.Model, Consumables.Color,
Consumables.Type,Cost,Yield  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
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.cpp  GROUP BY
subquery2.Make,subquery2.Model,
subquery2.Color,subquery2.Type,subquery1.cpp
 ORDER BY Make, Model;

Mike

In response to

Responses

pgsql-sql by date

Next:From: Oliveiros d'Azevedo CristinaDate: 2012-06-01 16:28:01
Subject: Re: Lowest 2 items per
Previous:From: Relyea, MikeDate: 2012-06-01 15:44:21
Subject: Re: Lowest 2 items per

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group