Thread: How to re-sort a sorted query?
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"
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?
Thanks..
Yudie
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 BYprice, 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@lfix.co.uk Isle of Wight http://www.lfix.co.uk/oliver GPG: 1024D/A54310EA 92C8 39E7 280E 3631 3F0E 1EC0 5664 7A2F A543 10EA ======================================== "Whosoever therefore shall be ashamed of me and of my words in this adulterousand sinful generation; of him also shall the Son of man be ashamed, when he cometh in the glory of hisFather with the holy angels." Mark 8:38
Oliver ,sorry, I didn't submit all complete fields as my example, The reason I didn't use agregate function because I still need to select another fields from storeproduct table and some outer joins. What about if the data in storeproduct table shows like this: ItemSku , StoreNumber , Price, Condition ==========================10001 , 7 , 30.00, Used10001 , 7 , 35.00, New <-- duplicate store number10001 , 5 , 45.00, New10001, 2 , 50.00, New However, should I use temporary table to make it simple? what about the performance? Yudie ----- Original Message ----- From: "Oliver Elphick" <olly@lfix.co.uk> To: "Yudie" <yudie@axiontech.com> Cc: <pgsql-sql@postgresql.org> Sent: Tuesday, October 26, 2004 3:34 PM Subject: Re: [SQL] 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 BYprice, 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@lfix.co.uk Isle of Wight http://www.lfix.co.uk/oliver GPG: 1024D/A54310EA 92C8 39E7 280E 3631 3F0E 1EC0 5664 7A2F A543 10EA ======================================== "Whosoever therefore shall be ashamed of me and of my words in this adulterousand sinful generation; of him also shall the Son of man be ashamed, when he cometh in the glory of hisFather with the holy angels." Mark 8:38 ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend
Oliver Elphick <olly@lfix.co.uk> writes:
> On Tue, 2004-10-26 at 14:23 -0500, Yudie wrote:
>> 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,
Sure it will. It's a perfectly good application of DISTINCT ON.
However, he has to use that particular ORDER BY to get the answers
he wants.
So the only way (I think) to change the ordering for display is to
wrap this as a sub-select:
select * from (select distinct on (storenumber), itemsku, storenumber,price from storeproduct where itemsku='10001'
orderby storenumber, price) ss
order by price;
regards, tom lane
On Tue, 2004-10-26 at 17:43 -0400, Tom Lane wrote: > Oliver Elphick <olly@lfix.co.uk> writes: > > On Tue, 2004-10-26 at 14:23 -0500, Yudie wrote: > >> 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, > > Sure it will. It's a perfectly good application of DISTINCT ON. > However, he has to use that particular ORDER BY to get the answers > he wants. Ah - because ORDER BY is applied before DISTINCT ON; I hadn't realised that. -- Oliver Elphick olly@lfix.co.uk Isle of Wight http://www.lfix.co.uk/oliver GPG: 1024D/A54310EA 92C8 39E7 280E 3631 3F0E 1EC0 5664 7A2F A543 10EA ======================================== "Whosoever therefore shall be ashamed of me and of my words in this adulterousand sinful generation; of him also shall the Son of man be ashamed, when he cometh in the glory of hisFather with the holy angels." Mark 8:38
> select * from > (select distinct on (storenumber), itemsku, storenumber,price > from storeproduct where itemsku='10001' > order by storenumber, price) ss > order by price; > > regards, tom lane Thanks tom, this is working. I never thought it could be done like this. yudie > > ---------------------------(end of broadcast)--------------------------- > TIP 6: Have you searched our list archives? > > http://archives.postgresql.org >