Re: How to re-sort a sorted query?

On Tue, 2004-10-26 at 14:23 -0500, Yudie wrote:
> I have a query that need to be sorted in order of price of store's
> product with unique store number.
>
> Here is a sample data of storeproduct table:
>
>
> ItemSku , StoreNumber , Price
> ==========================
> 10001 , 7 , 30.00
> 10001 , 7 , 35.00 <-- duplicate store number
> 10001 , 5 , 45.00
> 10001 , 2 , 50.00
>
> Then I do this query to get unique store number and also the cheapest
> price from each store:
>
> SQL= "Select distinct on (storenumber), itemsku, storenumber,price
> from storeproduct where itemsku='10001'
> order by storenumber, price"

That won't get you the cheapest price, just an arbitrary one determined
by the physical storage order.

You need to use GROUP BY with an aggregate function:

SELECT itemsku, storenumber, MIN(price)
FROM storeproduct WHERE itemsku = '10001'
GROUP BY itemsku, storenumber
ORDER BY price, storenumber;

> Result #1:
> ItemSku , StoreNumber , Price
> 10001 , 2 , 50.00
> 10001 , 5 , 45.00
> 10001 , 7 , 30.00
>
> The question is how to make the query that returns as above but sorted
> by price?

The literal answer to your question is to put price first in the ORDER
BY clause, but I'm not convinced you actually want to know something
that simple.

--
Oliver Elphick olly(at)lfix(dot)co(dot)uk
Isle of Wight http://www.lfix.co.uk/oliver
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