Re: Query to get the min of the total - Mailing list pgsql-novice
From | Oliveiros d'Azevedo Cristina |
---|---|
Subject | Re: Query to get the min of the total |
Date | |
Msg-id | 1572AA7A0B7B4EAA89EF4493BCD67611@marktestcr.marktest.pt Whole thread Raw |
In response to | Query to get the min of the total (Marta Pérez Romero <martape@gmail.com>) |
Responses |
Re: Query to get the min of the total
|
List | pgsql-novice |
Trickier.
Ok, subqueries revisited.
Please try this out and tell me if it worked.
This is untested code, I might have made some mistake, including syntactic :-)
SELECT *
FROM
(
SELECT petname,SUM(quantity) as total
FROM pets a
NATURAL JOIN sales b
GROUP BY petname
) x
NATURAL JOIN
(SELECT MIN(total) as total
FROM
(
SELECT petname,SUM(quantity) as total
FROM pets a
NATURAL JOIN sales b
GROUP BY petname
)y
)z
Best,
Oliveiros
----- Original Message -----From: Marta Pérez RomeroSent: Friday, May 04, 2012 11:39 AMSubject: Re: [NOVICE] Query to get the min of the totalJust a question related to this... what if there were two different pets with the same total quantity sold, both being the least sold?As we are saying LIMIT 1, only one would be displayed... how can I do so both (or 3, or 4) are displayed?On 4 May 2012 11:34, Marta Pérez Romero <martape@gmail.com> wrote:Yes! It works now, thanks a mill :):):)On 4 May 2012 11:23, Marta Pérez Romero <martape@gmail.com> wrote:Hiya Oliveiros,This looks much better now, although the results is not good yet :)By using the nested query this is what I have now:SELECT petname,min(total)FROM(SELECT petname,SUM(quantity) as totalFROM pets NATURAL JOIN salesGROUP BY petname) AS subqueryGROUP BY subquery.petnameAs a result, it gives me all the results: all petnames with the sum of quantity.If I change min(total) for max(total) or for sum(total), the result is the same, all petnames :(Thanks a lot!On 4 May 2012 11:05, Oliveiros d'Azevedo Cristina <oliveiros.cristina@marktest.pt> wrote:Howdy,Marta,have you tried a nested query?Something likeSELECT petname, MIN(total)FROM (SELECT petname,SUM(quantity) as totalFROM pets aNATURAL JOIN sales bGROUP BY petname) xBest,Oliveiros----- Original Message -----From: Marta Pérez RomeroSent: Friday, May 04, 2012 10:43 AMSubject: [NOVICE] Query to get the min of the totalHi All,I am trying to do something but cannot find the way.Hopefully you have some suggestions :)I have two tables, as follows:pets: with these columns: petcode, petname, petprice, petfamilysales: with these columns: salescode, petcode, quantityThe pets table contains all the pets in my pet shop, with the code of the pet, its name, its price and the family it belongs to.So for example:petcode | petname | petprice | petfamily------------------------------------------------------------1 | canary | 5.00 | birds2 | retriever | 12.00 | dogs3 | siamese | 28.00 | cats4 | sparrow | 7.00 | birds5 | poodle | 16.00 | dogsThe sales table tracks all the sales in the shop, with the code of the sale, the code of the pet that was bought, and the quantity of this pet bought.For example:salescode | petcode | quantity----------------------------------------------1 | 1 | 22 | 4 | 53 | 5 | 14 | 2 | 35 | 5 | 86 | 1 | 4Now, I need to build a query that returns the least sold pet, in quantity. It will include the pet name and the quantity sold.So in the example above it will be:petname | quantityretriever | 3Now, the problem I have is that I can´t work with nested aggregations.First I need to get the total quantity by petcode (which will be the sum of quantity). And then get the MIN of the SUM of quantity, which I don´t know how to do.This is the query so far:SELECTpets.petname,sum(sales.quantity)FROM sales INNER JOIN pets ON sales.petcode= pets.petcodeGROUP BYpets.petnameHAVING SUM(sales.quantity)=(SELECT MIN(quantity) FROM sales)ORDER BY pets.petname;But it does not return any result. How can I do it?Thanks very much
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