Need help with query

**John Gilson** · Jul 20 '05, 01:19 AM

Re: Need help with query

"netpurpose " <netpurpose@hot mail.com> wrote in message
news:31c57b38.0 308290040.6a560 bd6@posting.goo gle.com...[color=blue]
> I need to extract data from this table to find the lowest prices of
> each product as of today. The product will be listed/grouped by the
> name only, discarding the product code - I use SUBSTRING(Produ ctName,
> 1, CHARINDEX('(', ProductName)-2).
>
> I can get this result, but I had to use several views (totally
> inefficient). I think this can be done in one efficient/fast query,
> but I can't think of one.
>
> In the case that one query is not possible, is there other efficient
> way to get the results? There are about 300K records in the table.
>
> Any help is appreciated! Thanks a lot in advance!
>
> Thanks,
> Netpurpose[/color]

SELECT P1.ProductName, P1.Price
FROM ProductList AS P1
WHERE EffectiveDate <= CURRENT_TIMESTA MP AND
NOT EXISTS
(SELECT *
FROM ProductList AS P2
WHERE SUBSTRING(P1.Pr oductName, 1,
CHARINDEX('(', P1.ProductName) - 2) =
SUBSTRING(P2.Pr oductName, 1,
CHARINDEX('(', P2.ProductName) - 2) AND
P2.EffectiveDat e <= CURRENT_TIMESTA MP AND
P2.Price < P1.Price)

Regards,
jag
[color=blue]
>
> -----------------------START TABLE INFO-------------------------
>
> Here is the desired result (on 8/29/03):
>
> ProductName Price
> ---------------------------------------- ---------------------
> Product One 33.5000
> Product Three 40.4500
> Product Two 44.7500
>
>
> Here is the table info:
>
> CREATE TABLE [ProductList] (
> [Distributor] [nvarchar] (5) NULL ,
> [ProductName] [nvarchar] (40) NULL ,
> [Price] [money] NULL ,
> [EffectiveDate] [smalldatetime] NULL
> ) ON [PRIMARY]
>
>
> Table Data (comma delimited):
> *Sorry I can't list in insert commands as there are too many.
>
> "Manufacturer", "ProductName"," Price","Effecti veDate"
> "AAA","Prod uct One (MXT234)",1000, 2003-08-30 00:00:00
> "BBB","Prod uct One (MXT234)",1000, 2003-07-29 00:00:00
> "BBB","Prod uct One (MXT234)",28.15 ,2003-07-30 00:00:00
> "BBB","Prod uct One (MXT234)",35.22 ,2003-08-04 00:00:00
> "BBB","Prod uct One (MXT234)",35.22 ,2003-08-04 00:00:00
> "BBB","Prod uct One (MXT234)",1000, 2003-08-16 00:00:00
> "BBB","Prod uct One (MXT234)",33.8, 2003-08-27 00:00:00
> "CCC","Prod uct One (MXT234)",33.25 ,2003-08-31 00:00:00
> "DDD","Prod uct One (MXT234)",46.25 ,2003-01-02 00:00:00
> "EEE","Prod uct One (MXT234)",1000, 2003-08-30 00:00:00
> "FFF","Prod uct One (MXT234)",1000, 2003-08-30 00:00:00
> "GGG","Prod uct One (MXT234)",1000, 2003-09-01 00:00:00
> "HHH","Prod uct One (MXT234)",33.8, 2003-08-04 00:00:00
> "III","Prod uct One (MXT234)",1000, 2003-01-13 00:00:00
> "JJJ","Prod uct One (MXT234)",34.35 ,2003-07-30 00:00:00
> "JJJ","Prod uct One (MXT234)",34.35 ,2003-09-01 00:00:00
> "KKK","Prod uct One (MXT234)",1000, 2003-08-30 00:00:00
> "ZZZ","Prod uct One (MXT205)",54,20 03-01-13 00:00:00
> "AAA","Prod uct One (MXT205)",1000, 2003-08-30 00:00:00
> "BBB","Prod uct One (MXT205)",33.95 ,2003-07-27 00:00:00
> "BBB","Prod uct One (MXT205)",33.95 ,2003-07-29 00:00:00
> "BBB","Prod uct One (MXT205)",35.22 ,2003-08-04 00:00:00
> "BBB","Prod uct One (MXT205)",33.8, 2003-08-16 00:00:00
> "BBB","Prod uct One (MXT205)",33.5, 2003-08-27 00:00:00
> "CCC","Prod uct One (MXT205)",1000, 2003-08-30 00:00:00
> "DDD","Prod uct One (MXT205)",46.25 ,2003-01-02 00:00:00
> "EEE","Prod uct One (MXT205)",1000, 2003-08-30 00:00:00
> "FFF","Prod uct One (MXT205)",1000, 2003-08-30 00:00:00
> "GGG","Prod uct One (MXT205)",1000, 2003-09-01 00:00:00
> "HHH","Prod uct One (MXT205)",33.95 ,2003-08-04 00:00:00
> "III","Prod uct One (MXT205)",1000, 2003-01-13 00:00:00
> "JJJ","Prod uct One (MXT205)",34.35 ,2003-07-30 00:00:00
> "JJJ","Prod uct One (MXT205)",34.35 ,2003-09-01 00:00:00
> "KKK","Prod uct One (MXT205)",1000, 2003-08-30 00:00:00
> "ZZZ","Prod uct One (MXT548)",54,20 03-01-13 00:00:00
> "AAA","Prod uct One (MXT548)",25.04 ,2003-08-31 00:00:00
> "BBB","Prod uct One (MXT548)",33.95 ,2003-07-22 00:00:00
> "BBB","Prod uct One (MXT548)",33.95 ,2003-07-27 00:00:00
> "BBB","Prod uct One (MXT548)",35.22 ,2003-08-04 00:00:00
> "BBB","Prod uct One (MXT548)",33.8, 2003-08-16 00:00:00
> "BBB","Prod uct One (MXT548)",33.8, 2003-08-27 00:00:00
> "CCC","Prod uct One (MXT548)",1000, 2003-08-30 00:00:00
> "DDD","Prod uct One (MXT548)",46.25 ,2003-01-02 00:00:00
> "EEE","Prod uct One (MXT548)",1000, 2003-08-30 00:00:00
> "FFF","Prod uct One (MXT548)",1000, 2003-08-30 00:00:00
> "GGG","Prod uct One (MXT548)",1000, 2003-09-01 00:00:00
> "HHH","Prod uct One (MXT548)",33.8, 2003-08-04 00:00:00
> "III","Prod uct One (MXT548)",1000, 2003-01-13 00:00:00
> "JJJ","Prod uct One (MXT548)",34.35 ,2003-07-30 00:00:00
> "JJJ","Prod uct One (MXT548)",34.35 ,2003-09-01 00:00:00
> "KKK","Prod uct One (MXT548)",1000, 2003-08-30 00:00:00
> "ZZZ","Prod uct Two (DGT6789)",54,2 003-01-13 00:00:00
> "AAA","Prod uct Two (DGT6789)",1000 ,2003-08-30 00:00:00
> "BBB","Prod uct Two (DGT6789)",1000 ,2003-07-22 00:00:00
> "BBB","Prod uct Two (DGT6789)",44.7 5,2003-07-27 00:00:00
> "BBB","Prod uct Two (DGT6789)",44.7 5,2003-07-29 00:00:00
> "BBB","Prod uct Two (DGT6789)",44.3 5,2003-07-30 00:00:00
> "BBB","Prod uct Two (DGT6789)",44.7 5,2003-08-04 00:00:00
> "BBB","Prod uct Two (DGT6789)",44.7 5,2003-08-04 00:00:00
> "BBB","Prod uct Two (DGT6789)",1000 ,2003-08-23 00:00:00
> "BBB","Prod uct Two (DGT6789)",44.7 5,2003-08-27 00:00:00
> "CCC","Prod uct Two (DGT6789)",1000 ,2003-08-30 00:00:00
> "DDD","Prod uct Two (DGT6789)",46.2 5,2003-05-08 00:00:00
> "EEE","Prod uct Two (DGT6789)",1000 ,2003-08-30 00:00:00
> "FFF","Prod uct Two (DGT6789)",1000 ,2003-08-30 00:00:00
> "GGG","Prod uct Two (DGT6789)",1000 ,2003-09-01 00:00:00
> "HHH","Prod uct Two (DGT6789)",46.1 ,2003-08-04 00:00:00
> "III","Prod uct Two (DGT6789)",1000 ,2003-01-13 00:00:00
> "JJJ","Prod uct Two (DGT6789)",47.4 5,2003-08-04 00:00:00
> "JJJ","Prod uct Two (DGT6789)",47.4 5,2003-09-01 00:00:00
> "KKK","Prod uct Two (DGT6789)",44.7 5,2003-07-14 00:00:00
> "ZZZ","Prod uct Two (DGT6704)",54,2 003-01-13 00:00:00
> "AAA","Prod uct Two (DGT6704)",1000 ,2003-08-30 00:00:00
> "BBB","Prod uct Two (DGT6704)",45.5 ,2003-07-22 00:00:00
> "BBB","Prod uct Two (DGT6704)",46.1 ,2003-08-04 00:00:00
> "BBB","Prod uct Two (DGT6704)",46.1 ,2003-08-16 00:00:00
> "BBB","Prod uct Two (DGT6704)",44.7 5,2003-08-27 00:00:00
> "CCC","Prod uct Two (DGT6704)",1000 ,2003-08-30 00:00:00
> "DDD","Prod uct Two (DGT6704)",46.2 5,2003-05-08 00:00:00
> "EEE","Prod uct Two (DGT6704)",1000 ,2003-08-30 00:00:00
> "FFF","Prod uct Two (DGT6704)",1000 ,2003-08-30 00:00:00
> "GGG","Prod uct Two (DGT6704)",1000 ,2003-09-01 00:00:00
> "HHH","Prod uct Two (DGT6704)",46.1 ,2003-08-04 00:00:00
> "III","Prod uct Two (DGT6704)",1000 ,2003-01-13 00:00:00
> "JJJ","Prod uct Two (DGT6704)",47.4 5,2003-08-04 00:00:00
> "JJJ","Prod uct Two (DGT6704)",47.4 5,2003-09-01 00:00:00
> "KKK","Prod uct Two (DGT6704)",44.7 5,2003-07-14 00:00:00
> "ZZZ","Prod uct Three (QAT6785)",52,2 003-01-13 00:00:00
> "AAA","Prod uct Three (QAT6785)",1000 ,2003-08-30 00:00:00
> "BBB","Prod uct Three (QAT6785)",45.5 ,2003-07-22 00:00:00
> "BBB","Prod uct Three (QAT6785)",532. 25,2003-07-29 00:00:00
> "BBB","Prod uct Three (QAT6785)",1000 ,2003-07-30 00:00:00
> "BBB","Prod uct Three (QAT6785)",1000 ,2003-08-04 00:00:00
> "BBB","Prod uct Three (QAT6785)",46.1 ,2003-08-16 00:00:00
> "BBB","Prod uct Three (QAT6785)",44.7 5,2003-08-27 00:00:00
> "CCC","Prod uct Three (QAT6785)",42.6 5,2003-08-31 00:00:00
> "DDD","Prod uct Three (QAT6785)",46.2 5,2003-05-08 00:00:00
> "EEE","Prod uct Three (QAT6785)",1000 ,2003-08-30 00:00:00
> "FFF","Prod uct Three (QAT6785)",1000 ,2003-08-30 00:00:00
> "GGG","Prod uct Three (QAT6785)",1000 ,2003-09-01 00:00:00
> "HHH","Prod uct Three (QAT6785)",46.1 ,2003-08-04 00:00:00
> "III","Prod uct Three (QAT6785)",1000 ,2003-01-13 00:00:00
> "JJJ","Prod uct Three (QAT6785)",40.4 5,2003-08-04 00:00:00
> "JJJ","Prod uct Three (QAT6785)",40.4 5,2003-09-01 00:00:00
> "KKK","Prod uct Three (QAT6785)",44.7 5,2003-07-14 00:00:00
> "ZZZ","Prod uct Three (QAT556)",50.23 ,2003-01-13 00:00:00
> "AAA","Prod uct Three (QAT556)",1000, 2003-08-30 00:00:00
> "BBB","Prod uct Three (QAT556)",44.75 ,2003-07-22 00:00:00
> "BBB","Prod uct Three (QAT556)",532.2 5,2003-07-29 00:00:00
> "BBB","Prod uct Three (QAT556)",1000, 2003-07-30 00:00:00
> "BBB","Prod uct Three (QAT556)",1000, 2003-08-03 00:00:00
> "BBB","Prod uct Three (QAT556)",1000, 2003-08-04 00:00:00
> "BBB","Prod uct Three (QAT556)",44.75 ,2003-08-16 00:00:00
> "BBB","Prod uct Three (QAT556)",44.75 ,2003-08-27 00:00:00
> "CCC","Prod uct Three (QAT556)",1000, 2003-08-30 00:00:00
> "DDD","Prod uct Three (QAT556)",46.25 ,2003-05-08 00:00:00
> "EEE","Prod uct Three (QAT556)",1000, 2003-08-30 00:00:00
> "FFF","Prod uct Three (QAT556)",1000, 2003-08-30 00:00:00
> "GGG","Prod uct Three (QAT556)",1000, 2003-09-01 00:00:00
> "HHH","Prod uct Three (QAT556)",46.1, 2003-08-04 00:00:00
> "III","Prod uct Three (QAT556)",1000, 2003-01-13 00:00:00
> "JJJ","Prod uct Three (QAT556)",40.45 ,2003-08-04 00:00:00
> "JJJ","Prod uct Three (QAT556)",40.45 ,2003-09-01 00:00:00
> "KKK","Prod uct Three (QAT556)",44.75 ,2003-07-14 00:00:00
> "JJJ","Prod uct Three (QAT556)",40.15 ,2003-08-01 00:00:00[/color]

**John Gilson** · Jul 20 '05, 01:19 AM

Re: Need help with query

"netpurpose " <netpurpose@hot mail.com> wrote in message
news:31c57b38.0 308291024.6bd2a 29c@posting.goo gle.com...[color=blue]
> Hi Jag,
>
> Thank you for your response. I tried the query, but it gives me a
> different pricing result:
>
> ProductName Price
> ---------------------------------------- ---------------------
> Product One (MXT234) 28.1500
> Product Two (DGT6789) 44.3500
> Product Three (QAT556) 40.1500
>
> The correct result should be:
>
> ProductName Price
> ---------------------------------------- ---------------------
> Product One 33.5000
> Product Two 44.7500
> Product Three 40.4500
>
> The reason is because for Product One, Manufacturer "BBB" has a price
> of 28.15 on 2003-07-30, this price is no longer valid because "BBB"
> has more recent price of 33.5 starting on 2003-08-27. Same case with
> Product Two and Three (manufacturer "JJJ" overrides the 40.15 on
> 2003-08-01 with 40.45 on 2003-08-04).
>
> I have to take the most recent prices from each manufacturer for a
> particular product (price at the latest date as of today), and then
> take the minimum price from the result.
>
> Again, thank you for your help. Sorry I might not explain it well in
> the beginning. Any further help is appreciated. Thank you very much
> in advance!
>
> Regards,
> Netpurpose[/color]

I was a little too quick on the draw and misread your requirements.

SELECT ProductName, MIN(Price)
FROM (SELECT P1.Distributor,
SUBSTRING(P1.Pr oductName, 1,
CHARINDEX('(', P1.ProductName) - 2) AS
ProductName,
P1.EffectiveDat e AS LatestDate,
P1.price
FROM ProductList AS P1
LEFT OUTER JOIN
ProductList AS P2
ON P1.Distributor = P2.Distributor AND
P1.ProductName = P2.ProductName AND
P1.EffectiveDat e <= CURRENT_TIMESTA MP AND
P2.EffectiveDat e <= CURRENT_TIMESTA MP AND
P2.EffectiveDat e > P1.EffectiveDat e
WHERE P2.EffectiveDat e IS NULL) AS LatestPrices
GROUP BY ProductName

Regards,
jag
[color=blue]
> "John Gilson" <jag@acm.org> wrote in message news:<_uI3b.514 41$ev.11935402@ twister.nyc.rr. com>...[color=green]
> > "netpurpose " <netpurpose@hot mail.com> wrote in message
> > news:31c57b38.0 308290040.6a560 bd6@posting.goo gle.com...[color=darkred]
> > > I need to extract data from this table to find the lowest prices of
> > > each product as of today. The product will be listed/grouped by the
> > > name only, discarding the product code - I use SUBSTRING(Produ ctName,
> > > 1, CHARINDEX('(', ProductName)-2).
> > >
> > > I can get this result, but I had to use several views (totally
> > > inefficient). I think this can be done in one efficient/fast query,
> > > but I can't think of one.
> > >
> > > In the case that one query is not possible, is there other efficient
> > > way to get the results? There are about 300K records in the table.
> > >
> > > Any help is appreciated! Thanks a lot in advance!
> > >
> > > Thanks,
> > > Netpurpose[/color]
> >
> > SELECT P1.ProductName, P1.Price
> > FROM ProductList AS P1
> > WHERE EffectiveDate <= CURRENT_TIMESTA MP AND
> > NOT EXISTS
> > (SELECT *
> > FROM ProductList AS P2
> > WHERE SUBSTRING(P1.Pr oductName, 1,
> > CHARINDEX('(', P1.ProductName) - 2) =
> > SUBSTRING(P2.Pr oductName, 1,
> > CHARINDEX('(', P2.ProductName) - 2) AND
> > P2.EffectiveDat e <= CURRENT_TIMESTA MP AND
> > P2.Price < P1.Price)
> >
> > Regards,
> > jag
> >[color=darkred]
> > >
> > > -----------------------START TABLE INFO-------------------------
> > >
> > > Here is the desired result (on 8/29/03):
> > >
> > > ProductName Price
> > > ---------------------------------------- ---------------------
> > > Product One 33.5000
> > > Product Three 40.4500
> > > Product Two 44.7500
> > >
> > >
> > > Here is the table info:
> > >
> > > CREATE TABLE [ProductList] (
> > > [Distributor] [nvarchar] (5) NULL ,
> > > [ProductName] [nvarchar] (40) NULL ,
> > > [Price] [money] NULL ,
> > > [EffectiveDate] [smalldatetime] NULL
> > > ) ON [PRIMARY]
> > >
> > >
> > > Table Data (comma delimited):
> > > *Sorry I can't list in insert commands as there are too many.
> > >
> > > "Manufacturer", "ProductName"," Price","Effecti veDate"
> > > "AAA","Prod uct One (MXT234)",1000, 2003-08-30 00:00:00
> > > "BBB","Prod uct One (MXT234)",1000, 2003-07-29 00:00:00
> > > "BBB","Prod uct One (MXT234)",28.15 ,2003-07-30 00:00:00
> > > "BBB","Prod uct One (MXT234)",35.22 ,2003-08-04 00:00:00
> > > "BBB","Prod uct One (MXT234)",35.22 ,2003-08-04 00:00:00
> > > "BBB","Prod uct One (MXT234)",1000, 2003-08-16 00:00:00
> > > "BBB","Prod uct One (MXT234)",33.8, 2003-08-27 00:00:00
> > > "CCC","Prod uct One (MXT234)",33.25 ,2003-08-31 00:00:00
> > > "DDD","Prod uct One (MXT234)",46.25 ,2003-01-02 00:00:00
> > > "EEE","Prod uct One (MXT234)",1000, 2003-08-30 00:00:00
> > > "FFF","Prod uct One (MXT234)",1000, 2003-08-30 00:00:00
> > > "GGG","Prod uct One (MXT234)",1000, 2003-09-01 00:00:00
> > > "HHH","Prod uct One (MXT234)",33.8, 2003-08-04 00:00:00
> > > "III","Prod uct One (MXT234)",1000, 2003-01-13 00:00:00
> > > "JJJ","Prod uct One (MXT234)",34.35 ,2003-07-30 00:00:00
> > > "JJJ","Prod uct One (MXT234)",34.35 ,2003-09-01 00:00:00
> > > "KKK","Prod uct One (MXT234)",1000, 2003-08-30 00:00:00
> > > "ZZZ","Prod uct One (MXT205)",54,20 03-01-13 00:00:00
> > > "AAA","Prod uct One (MXT205)",1000, 2003-08-30 00:00:00
> > > "BBB","Prod uct One (MXT205)",33.95 ,2003-07-27 00:00:00
> > > "BBB","Prod uct One (MXT205)",33.95 ,2003-07-29 00:00:00
> > > "BBB","Prod uct One (MXT205)",35.22 ,2003-08-04 00:00:00
> > > "BBB","Prod uct One (MXT205)",33.8, 2003-08-16 00:00:00
> > > "BBB","Prod uct One (MXT205)",33.5, 2003-08-27 00:00:00
> > > "CCC","Prod uct One (MXT205)",1000, 2003-08-30 00:00:00
> > > "DDD","Prod uct One (MXT205)",46.25 ,2003-01-02 00:00:00
> > > "EEE","Prod uct One (MXT205)",1000, 2003-08-30 00:00:00
> > > "FFF","Prod uct One (MXT205)",1000, 2003-08-30 00:00:00
> > > "GGG","Prod uct One (MXT205)",1000, 2003-09-01 00:00:00
> > > "HHH","Prod uct One (MXT205)",33.95 ,2003-08-04 00:00:00
> > > "III","Prod uct One (MXT205)",1000, 2003-01-13 00:00:00
> > > "JJJ","Prod uct One (MXT205)",34.35 ,2003-07-30 00:00:00
> > > "JJJ","Prod uct One (MXT205)",34.35 ,2003-09-01 00:00:00
> > > "KKK","Prod uct One (MXT205)",1000, 2003-08-30 00:00:00
> > > "ZZZ","Prod uct One (MXT548)",54,20 03-01-13 00:00:00
> > > "AAA","Prod uct One (MXT548)",25.04 ,2003-08-31 00:00:00
> > > "BBB","Prod uct One (MXT548)",33.95 ,2003-07-22 00:00:00
> > > "BBB","Prod uct One (MXT548)",33.95 ,2003-07-27 00:00:00
> > > "BBB","Prod uct One (MXT548)",35.22 ,2003-08-04 00:00:00
> > > "BBB","Prod uct One (MXT548)",33.8, 2003-08-16 00:00:00
> > > "BBB","Prod uct One (MXT548)",33.8, 2003-08-27 00:00:00
> > > "CCC","Prod uct One (MXT548)",1000, 2003-08-30 00:00:00
> > > "DDD","Prod uct One (MXT548)",46.25 ,2003-01-02 00:00:00
> > > "EEE","Prod uct One (MXT548)",1000, 2003-08-30 00:00:00
> > > "FFF","Prod uct One (MXT548)",1000, 2003-08-30 00:00:00
> > > "GGG","Prod uct One (MXT548)",1000, 2003-09-01 00:00:00
> > > "HHH","Prod uct One (MXT548)",33.8, 2003-08-04 00:00:00
> > > "III","Prod uct One (MXT548)",1000, 2003-01-13 00:00:00
> > > "JJJ","Prod uct One (MXT548)",34.35 ,2003-07-30 00:00:00
> > > "JJJ","Prod uct One (MXT548)",34.35 ,2003-09-01 00:00:00
> > > "KKK","Prod uct One (MXT548)",1000, 2003-08-30 00:00:00
> > > "ZZZ","Prod uct Two (DGT6789)",54,2 003-01-13 00:00:00
> > > "AAA","Prod uct Two (DGT6789)",1000 ,2003-08-30 00:00:00
> > > "BBB","Prod uct Two (DGT6789)",1000 ,2003-07-22 00:00:00
> > > "BBB","Prod uct Two (DGT6789)",44.7 5,2003-07-27 00:00:00
> > > "BBB","Prod uct Two (DGT6789)",44.7 5,2003-07-29 00:00:00
> > > "BBB","Prod uct Two (DGT6789)",44.3 5,2003-07-30 00:00:00
> > > "BBB","Prod uct Two (DGT6789)",44.7 5,2003-08-04 00:00:00
> > > "BBB","Prod uct Two (DGT6789)",44.7 5,2003-08-04 00:00:00
> > > "BBB","Prod uct Two (DGT6789)",1000 ,2003-08-23 00:00:00
> > > "BBB","Prod uct Two (DGT6789)",44.7 5,2003-08-27 00:00:00
> > > "CCC","Prod uct Two (DGT6789)",1000 ,2003-08-30 00:00:00
> > > "DDD","Prod uct Two (DGT6789)",46.2 5,2003-05-08 00:00:00
> > > "EEE","Prod uct Two (DGT6789)",1000 ,2003-08-30 00:00:00
> > > "FFF","Prod uct Two (DGT6789)",1000 ,2003-08-30 00:00:00
> > > "GGG","Prod uct Two (DGT6789)",1000 ,2003-09-01 00:00:00
> > > "HHH","Prod uct Two (DGT6789)",46.1 ,2003-08-04 00:00:00
> > > "III","Prod uct Two (DGT6789)",1000 ,2003-01-13 00:00:00
> > > "JJJ","Prod uct Two (DGT6789)",47.4 5,2003-08-04 00:00:00
> > > "JJJ","Prod uct Two (DGT6789)",47.4 5,2003-09-01 00:00:00
> > > "KKK","Prod uct Two (DGT6789)",44.7 5,2003-07-14 00:00:00
> > > "ZZZ","Prod uct Two (DGT6704)",54,2 003-01-13 00:00:00
> > > "AAA","Prod uct Two (DGT6704)",1000 ,2003-08-30 00:00:00
> > > "BBB","Prod uct Two (DGT6704)",45.5 ,2003-07-22 00:00:00
> > > "BBB","Prod uct Two (DGT6704)",46.1 ,2003-08-04 00:00:00
> > > "BBB","Prod uct Two (DGT6704)",46.1 ,2003-08-16 00:00:00
> > > "BBB","Prod uct Two (DGT6704)",44.7 5,2003-08-27 00:00:00
> > > "CCC","Prod uct Two (DGT6704)",1000 ,2003-08-30 00:00:00
> > > "DDD","Prod uct Two (DGT6704)",46.2 5,2003-05-08 00:00:00
> > > "EEE","Prod uct Two (DGT6704)",1000 ,2003-08-30 00:00:00
> > > "FFF","Prod uct Two (DGT6704)",1000 ,2003-08-30 00:00:00
> > > "GGG","Prod uct Two (DGT6704)",1000 ,2003-09-01 00:00:00
> > > "HHH","Prod uct Two (DGT6704)",46.1 ,2003-08-04 00:00:00
> > > "III","Prod uct Two (DGT6704)",1000 ,2003-01-13 00:00:00
> > > "JJJ","Prod uct Two (DGT6704)",47.4 5,2003-08-04 00:00:00
> > > "JJJ","Prod uct Two (DGT6704)",47.4 5,2003-09-01 00:00:00
> > > "KKK","Prod uct Two (DGT6704)",44.7 5,2003-07-14 00:00:00
> > > "ZZZ","Prod uct Three (QAT6785)",52,2 003-01-13 00:00:00
> > > "AAA","Prod uct Three (QAT6785)",1000 ,2003-08-30 00:00:00
> > > "BBB","Prod uct Three (QAT6785)",45.5 ,2003-07-22 00:00:00
> > > "BBB","Prod uct Three (QAT6785)",532. 25,2003-07-29 00:00:00
> > > "BBB","Prod uct Three (QAT6785)",1000 ,2003-07-30 00:00:00
> > > "BBB","Prod uct Three (QAT6785)",1000 ,2003-08-04 00:00:00
> > > "BBB","Prod uct Three (QAT6785)",46.1 ,2003-08-16 00:00:00
> > > "BBB","Prod uct Three (QAT6785)",44.7 5,2003-08-27 00:00:00
> > > "CCC","Prod uct Three (QAT6785)",42.6 5,2003-08-31 00:00:00
> > > "DDD","Prod uct Three (QAT6785)",46.2 5,2003-05-08 00:00:00
> > > "EEE","Prod uct Three (QAT6785)",1000 ,2003-08-30 00:00:00
> > > "FFF","Prod uct Three (QAT6785)",1000 ,2003-08-30 00:00:00
> > > "GGG","Prod uct Three (QAT6785)",1000 ,2003-09-01 00:00:00
> > > "HHH","Prod uct Three (QAT6785)",46.1 ,2003-08-04 00:00:00
> > > "III","Prod uct Three (QAT6785)",1000 ,2003-01-13 00:00:00
> > > "JJJ","Prod uct Three (QAT6785)",40.4 5,2003-08-04 00:00:00
> > > "JJJ","Prod uct Three (QAT6785)",40.4 5,2003-09-01 00:00:00
> > > "KKK","Prod uct Three (QAT6785)",44.7 5,2003-07-14 00:00:00
> > > "ZZZ","Prod uct Three (QAT556)",50.23 ,2003-01-13 00:00:00
> > > "AAA","Prod uct Three (QAT556)",1000, 2003-08-30 00:00:00
> > > "BBB","Prod uct Three (QAT556)",44.75 ,2003-07-22 00:00:00
> > > "BBB","Prod uct Three (QAT556)",532.2 5,2003-07-29 00:00:00
> > > "BBB","Prod uct Three (QAT556)",1000, 2003-07-30 00:00:00
> > > "BBB","Prod uct Three (QAT556)",1000, 2003-08-03 00:00:00
> > > "BBB","Prod uct Three (QAT556)",1000, 2003-08-04 00:00:00
> > > "BBB","Prod uct Three (QAT556)",44.75 ,2003-08-16 00:00:00
> > > "BBB","Prod uct Three (QAT556)",44.75 ,2003-08-27 00:00:00
> > > "CCC","Prod uct Three (QAT556)",1000, 2003-08-30 00:00:00
> > > "DDD","Prod uct Three (QAT556)",46.25 ,2003-05-08 00:00:00
> > > "EEE","Prod uct Three (QAT556)",1000, 2003-08-30 00:00:00
> > > "FFF","Prod uct Three (QAT556)",1000, 2003-08-30 00:00:00
> > > "GGG","Prod uct Three (QAT556)",1000, 2003-09-01 00:00:00
> > > "HHH","Prod uct Three (QAT556)",46.1, 2003-08-04 00:00:00
> > > "III","Prod uct Three (QAT556)",1000, 2003-01-13 00:00:00
> > > "JJJ","Prod uct Three (QAT556)",40.45 ,2003-08-04 00:00:00
> > > "JJJ","Prod uct Three (QAT556)",40.45 ,2003-09-01 00:00:00
> > > "KKK","Prod uct Three (QAT556)",44.75 ,2003-07-14 00:00:00
> > > "JJJ","Prod uct Three (QAT556)",40.15 ,2003-08-01 00:00:00[/color][/color][/color]

**Steve Kass** · Jul 20 '05, 01:19 AM

Re: Need help with query

Did I miscopy John's query? It gives me the future price of $25.04
for Product One, but is easy to fix by adding

AND P1.EffectiveDat e <= CURRENT_TIMESTA MP

to the where clause of the derived table LatestPrices

John's initial idea of NOT EXISTS still works, too, in part. (Note
that I blew off the ProductName parsing by taking a hatchet to that
column with an update...

-- Be lazy
UPDATE ProductList SET
ProductName =
SUBSTRING(Produ ctName, 1,CHARINDEX('(' , ProductName) - 2)
GO

-- For each product, select the lowest non-future
-- price that has not been superseded.
SELECT ProductName, MIN(Price) as Price -- get the lowest price
FROM (
SELECT ProductName, Price -- from all non-future prices
FROM ProductList P1
WHERE P1.EffectiveDat e <= CURRENT_TIMESTA MP
AND NOT EXISTS ( -- that have not been superseded
SELECT * FROM ProductList P2
WHERE P2.Distributor = P1.Distributor
AND P2.ProductName = P1.ProductName
AND P2.EffectiveDat e <= CURRENT_TIMESTA MP
AND P2.EffectiveDat e > P1.EffectiveDat e
)
) T
GROUP BY ProductName -- for each product
go

By the way, the delimited data was no trouble. I pasted it into
Excel, did Text To Columns, named the data region, and inserted it with:

insert into [ProductList]
select Manufacturer, ProductName, Price, EffectiveDate
from OpenRowset(
'Microsoft.Jet. OLEDB.4.0',
'Excel 8.0;Database=e: \excel\ProductL ist.xls',
'select * from ProductList')

Be sure to close the Excel file before inserting.

-- Steve Kass
-- Drew University
-- Ref: 2498EA13-1756-4C81-9307-25AFD5BB451D

netpurpose wrote:[color=blue]
> Hi Jag,
>
> Thanks a lot!! It works like a charm! Your query saves me a lot of headache.
>
> I have struggled with this for quite a while now and I am glad I find help here.
>
> Again, thank you very much! I really appreciate your help in such a short time!
>
> Regards,
> Netpurpose
>
>
> "John Gilson" <jag@acm.org> wrote in message news:<amO3b.521 63$ev.12155054@ twister.nyc.rr. com>...
>[color=green]
>>"netpurpose " <netpurpose@hot mail.com> wrote in message
>>news:31c57b38 .0308291024.6bd 2a29c@posting.g oogle.com...
>>[color=darkred]
>>>Hi Jag,
>>>
>>>Thank you for your response. I tried the query, but it gives me a
>>>different pricing result:
>>>
>>>ProductNam e Price
>>>---------------------------------------- ---------------------
>>>Product One (MXT234) 28.1500
>>>Product Two (DGT6789) 44.3500
>>>Product Three (QAT556) 40.1500
>>>
>>>The correct result should be:
>>>
>>>ProductNam e Price
>>>---------------------------------------- ---------------------
>>>Product One 33.5000
>>>Product Two 44.7500
>>>Product Three 40.4500
>>>
>>>The reason is because for Product One, Manufacturer "BBB" has a price
>>>of 28.15 on 2003-07-30, this price is no longer valid because "BBB"
>>>has more recent price of 33.5 starting on 2003-08-27. Same case with
>>>Product Two and Three (manufacturer "JJJ" overrides the 40.15 on
>>>2003-08-01 with 40.45 on 2003-08-04).
>>>
>>>I have to take the most recent prices from each manufacturer for a
>>>particular product (price at the latest date as of today), and then
>>>take the minimum price from the result.
>>>
>>>Again, thank you for your help. Sorry I might not explain it well in
>>>the beginning. Any further help is appreciated. Thank you very much
>>>in advance!
>>>
>>>Regards,
>>>Netpurpose[/color]
>>
>>I was a little too quick on the draw and misread your requirements.
>>
>>SELECT ProductName, MIN(Price)
>>FROM (SELECT P1.Distributor,
>> SUBSTRING(P1.Pr oductName, 1,
>> CHARINDEX('(', P1.ProductName) - 2) AS
>> ProductName,
>> P1.EffectiveDat e AS LatestDate,
>> P1.price
>> FROM ProductList AS P1
>> LEFT OUTER JOIN
>> ProductList AS P2
>> ON P1.Distributor = P2.Distributor AND
>> P1.ProductName = P2.ProductName AND
>> P1.EffectiveDat e <= CURRENT_TIMESTA MP AND
>> P2.EffectiveDat e <= CURRENT_TIMESTA MP AND
>> P2.EffectiveDat e > P1.EffectiveDat e
>> WHERE P2.EffectiveDat e IS NULL) AS LatestPrices
>>GROUP BY ProductName
>>
>>Regards,
>>jag
>>
>>[color=darkred]
>>>"John Gilson" <jag@acm.org> wrote in message news:<_uI3b.514 41$ev.11935402@ twister.nyc.rr. com>...
>>>
>>>>"netpurpose " <netpurpose@hot mail.com> wrote in message
>>>>news:31c57b 38.0308290040.6 a560bd6@posting .google.com...
>>>>
>>>>>I need to extract data from this table to find the lowest prices of
>>>>>each product as of today. The product will be listed/grouped by the
>>>>>name only, discarding the product code - I use SUBSTRING(Produ ctName,
>>>>>1, CHARINDEX('(', ProductName)-2).
>>>>>
>>>>>I can get this result, but I had to use several views (totally
>>>>>inefficien t). I think this can be done in one efficient/fast query,
>>>>>but I can't think of one.
>>>>>
>>>>>In the case that one query is not possible, is there other efficient
>>>>>way to get the results? There are about 300K records in the table.
>>>>>
>>>>>Any help is appreciated! Thanks a lot in advance!
>>>>>
>>>>>Thanks,
>>>>>Netpurpo se
>>>>
>>>>SELECT P1.ProductName, P1.Price
>>>>FROM ProductList AS P1
>>>>WHERE EffectiveDate <= CURRENT_TIMESTA MP AND
>>>> NOT EXISTS
>>>> (SELECT *
>>>> FROM ProductList AS P2
>>>> WHERE SUBSTRING(P1.Pr oductName, 1,
>>>> CHARINDEX('(', P1.ProductName) - 2) =
>>>> SUBSTRING(P2.Pr oductName, 1,
>>>> CHARINDEX('(', P2.ProductName) - 2) AND
>>>> P2.EffectiveDat e <= CURRENT_TIMESTA MP AND
>>>> P2.Price < P1.Price)
>>>>
>>>>Regards,
>>>>jag
>>>>
>>>>
>>>>>-----------------------START TABLE INFO-------------------------
>>>>>
>>>>>Here is the desired result (on 8/29/03):
>>>>>
>>>>>ProductNam e Price
>>>>>---------------------------------------- ---------------------
>>>>>Product One 33.5000
>>>>>Product Three 40.4500
>>>>>Product Two 44.7500
>>>>>
>>>>>
>>>>>Here is the table info:
>>>>>
>>>>>CREATE TABLE [ProductList] (
>>>>>[Distributor] [nvarchar] (5) NULL ,
>>>>>[ProductName] [nvarchar] (40) NULL ,
>>>>>[Price] [money] NULL ,
>>>>>[EffectiveDate] [smalldatetime] NULL
>>>>>) ON [PRIMARY]
>>>>>
>>>>>
>>>>>Table Data (comma delimited):
>>>>>*Sorry I can't list in insert commands as there are too many.
>>>>>
>>>>>"Manufactu rer","ProductNa me","Price","Ef fectiveDate"
>>>>>"AAA","Pro duct One (MXT234)",1000, 2003-08-30 00:00:00
>>>>>"BBB","Pro duct One (MXT234)",1000, 2003-07-29 00:00:00
>>>>>"BBB","Pro duct One (MXT234)",28.15 ,2003-07-30 00:00:00
>>>>>"BBB","Pro duct One (MXT234)",35.22 ,2003-08-04 00:00:00
>>>>>"BBB","Pro duct One (MXT234)",35.22 ,2003-08-04 00:00:00
>>>>>"BBB","Pro duct One (MXT234)",1000, 2003-08-16 00:00:00
>>>>>"BBB","Pro duct One (MXT234)",33.8, 2003-08-27 00:00:00
>>>>>"CCC","Pro duct One (MXT234)",33.25 ,2003-08-31 00:00:00
>>>>>"DDD","Pro duct One (MXT234)",46.25 ,2003-01-02 00:00:00
>>>>>"EEE","Pro duct One (MXT234)",1000, 2003-08-30 00:00:00
>>>>>"FFF","Pro duct One (MXT234)",1000, 2003-08-30 00:00:00
>>>>>"GGG","Pro duct One (MXT234)",1000, 2003-09-01 00:00:00
>>>>>"HHH","Pro duct One (MXT234)",33.8, 2003-08-04 00:00:00
>>>>>"III","Pro duct One (MXT234)",1000, 2003-01-13 00:00:00
>>>>>"JJJ","Pro duct One (MXT234)",34.35 ,2003-07-30 00:00:00
>>>>>"JJJ","Pro duct One (MXT234)",34.35 ,2003-09-01 00:00:00
>>>>>"KKK","Pro duct One (MXT234)",1000, 2003-08-30 00:00:00
>>>>>"ZZZ","Pro duct One (MXT205)",54,20 03-01-13 00:00:00
>>>>>"AAA","Pro duct One (MXT205)",1000, 2003-08-30 00:00:00
>>>>>"BBB","Pro duct One (MXT205)",33.95 ,2003-07-27 00:00:00
>>>>>"BBB","Pro duct One (MXT205)",33.95 ,2003-07-29 00:00:00
>>>>>"BBB","Pro duct One (MXT205)",35.22 ,2003-08-04 00:00:00
>>>>>"BBB","Pro duct One (MXT205)",33.8, 2003-08-16 00:00:00
>>>>>"BBB","Pro duct One (MXT205)",33.5, 2003-08-27 00:00:00
>>>>>"CCC","Pro duct One (MXT205)",1000, 2003-08-30 00:00:00
>>>>>"DDD","Pro duct One (MXT205)",46.25 ,2003-01-02 00:00:00
>>>>>"EEE","Pro duct One (MXT205)",1000, 2003-08-30 00:00:00
>>>>>"FFF","Pro duct One (MXT205)",1000, 2003-08-30 00:00:00
>>>>>"GGG","Pro duct One (MXT205)",1000, 2003-09-01 00:00:00
>>>>>"HHH","Pro duct One (MXT205)",33.95 ,2003-08-04 00:00:00
>>>>>"III","Pro duct One (MXT205)",1000, 2003-01-13 00:00:00
>>>>>"JJJ","Pro duct One (MXT205)",34.35 ,2003-07-30 00:00:00
>>>>>"JJJ","Pro duct One (MXT205)",34.35 ,2003-09-01 00:00:00
>>>>>"KKK","Pro duct One (MXT205)",1000, 2003-08-30 00:00:00
>>>>>"ZZZ","Pro duct One (MXT548)",54,20 03-01-13 00:00:00
>>>>>"AAA","Pro duct One (MXT548)",25.04 ,2003-08-31 00:00:00
>>>>>"BBB","Pro duct One (MXT548)",33.95 ,2003-07-22 00:00:00
>>>>>"BBB","Pro duct One (MXT548)",33.95 ,2003-07-27 00:00:00
>>>>>"BBB","Pro duct One (MXT548)",35.22 ,2003-08-04 00:00:00
>>>>>"BBB","Pro duct One (MXT548)",33.8, 2003-08-16 00:00:00
>>>>>"BBB","Pro duct One (MXT548)",33.8, 2003-08-27 00:00:00
>>>>>"CCC","Pro duct One (MXT548)",1000, 2003-08-30 00:00:00
>>>>>"DDD","Pro duct One (MXT548)",46.25 ,2003-01-02 00:00:00
>>>>>"EEE","Pro duct One (MXT548)",1000, 2003-08-30 00:00:00
>>>>>"FFF","Pro duct One (MXT548)",1000, 2003-08-30 00:00:00
>>>>>"GGG","Pro duct One (MXT548)",1000, 2003-09-01 00:00:00
>>>>>"HHH","Pro duct One (MXT548)",33.8, 2003-08-04 00:00:00
>>>>>"III","Pro duct One (MXT548)",1000, 2003-01-13 00:00:00
>>>>>"JJJ","Pro duct One (MXT548)",34.35 ,2003-07-30 00:00:00
>>>>>"JJJ","Pro duct One (MXT548)",34.35 ,2003-09-01 00:00:00
>>>>>"KKK","Pro duct One (MXT548)",1000, 2003-08-30 00:00:00
>>>>>"ZZZ","Pro duct Two (DGT6789)",54,2 003-01-13 00:00:00
>>>>>"AAA","Pro duct Two (DGT6789)",1000 ,2003-08-30 00:00:00
>>>>>"BBB","Pro duct Two (DGT6789)",1000 ,2003-07-22 00:00:00
>>>>>"BBB","Pro duct Two (DGT6789)",44.7 5,2003-07-27 00:00:00
>>>>>"BBB","Pro duct Two (DGT6789)",44.7 5,2003-07-29 00:00:00
>>>>>"BBB","Pro duct Two (DGT6789)",44.3 5,2003-07-30 00:00:00
>>>>>"BBB","Pro duct Two (DGT6789)",44.7 5,2003-08-04 00:00:00
>>>>>"BBB","Pro duct Two (DGT6789)",44.7 5,2003-08-04 00:00:00
>>>>>"BBB","Pro duct Two (DGT6789)",1000 ,2003-08-23 00:00:00
>>>>>"BBB","Pro duct Two (DGT6789)",44.7 5,2003-08-27 00:00:00
>>>>>"CCC","Pro duct Two (DGT6789)",1000 ,2003-08-30 00:00:00
>>>>>"DDD","Pro duct Two (DGT6789)",46.2 5,2003-05-08 00:00:00
>>>>>"EEE","Pro duct Two (DGT6789)",1000 ,2003-08-30 00:00:00
>>>>>"FFF","Pro duct Two (DGT6789)",1000 ,2003-08-30 00:00:00
>>>>>"GGG","Pro duct Two (DGT6789)",1000 ,2003-09-01 00:00:00
>>>>>"HHH","Pro duct Two (DGT6789)",46.1 ,2003-08-04 00:00:00
>>>>>"III","Pro duct Two (DGT6789)",1000 ,2003-01-13 00:00:00
>>>>>"JJJ","Pro duct Two (DGT6789)",47.4 5,2003-08-04 00:00:00
>>>>>"JJJ","Pro duct Two (DGT6789)",47.4 5,2003-09-01 00:00:00
>>>>>"KKK","Pro duct Two (DGT6789)",44.7 5,2003-07-14 00:00:00
>>>>>"ZZZ","Pro duct Two (DGT6704)",54,2 003-01-13 00:00:00
>>>>>"AAA","Pro duct Two (DGT6704)",1000 ,2003-08-30 00:00:00
>>>>>"BBB","Pro duct Two (DGT6704)",45.5 ,2003-07-22 00:00:00
>>>>>"BBB","Pro duct Two (DGT6704)",46.1 ,2003-08-04 00:00:00
>>>>>"BBB","Pro duct Two (DGT6704)",46.1 ,2003-08-16 00:00:00
>>>>>"BBB","Pro duct Two (DGT6704)",44.7 5,2003-08-27 00:00:00
>>>>>"CCC","Pro duct Two (DGT6704)",1000 ,2003-08-30 00:00:00
>>>>>"DDD","Pro duct Two (DGT6704)",46.2 5,2003-05-08 00:00:00
>>>>>"EEE","Pro duct Two (DGT6704)",1000 ,2003-08-30 00:00:00
>>>>>"FFF","Pro duct Two (DGT6704)",1000 ,2003-08-30 00:00:00
>>>>>"GGG","Pro duct Two (DGT6704)",1000 ,2003-09-01 00:00:00
>>>>>"HHH","Pro duct Two (DGT6704)",46.1 ,2003-08-04 00:00:00
>>>>>"III","Pro duct Two (DGT6704)",1000 ,2003-01-13 00:00:00
>>>>>"JJJ","Pro duct Two (DGT6704)",47.4 5,2003-08-04 00:00:00
>>>>>"JJJ","Pro duct Two (DGT6704)",47.4 5,2003-09-01 00:00:00
>>>>>"KKK","Pro duct Two (DGT6704)",44.7 5,2003-07-14 00:00:00
>>>>>"ZZZ","Pro duct Three (QAT6785)",52,2 003-01-13 00:00:00
>>>>>"AAA","Pro duct Three (QAT6785)",1000 ,2003-08-30 00:00:00
>>>>>"BBB","Pro duct Three (QAT6785)",45.5 ,2003-07-22 00:00:00
>>>>>"BBB","Pro duct Three (QAT6785)",532. 25,2003-07-29 00:00:00
>>>>>"BBB","Pro duct Three (QAT6785)",1000 ,2003-07-30 00:00:00
>>>>>"BBB","Pro duct Three (QAT6785)",1000 ,2003-08-04 00:00:00
>>>>>"BBB","Pro duct Three (QAT6785)",46.1 ,2003-08-16 00:00:00
>>>>>"BBB","Pro duct Three (QAT6785)",44.7 5,2003-08-27 00:00:00
>>>>>"CCC","Pro duct Three (QAT6785)",42.6 5,2003-08-31 00:00:00
>>>>>"DDD","Pro duct Three (QAT6785)",46.2 5,2003-05-08 00:00:00
>>>>>"EEE","Pro duct Three (QAT6785)",1000 ,2003-08-30 00:00:00
>>>>>"FFF","Pro duct Three (QAT6785)",1000 ,2003-08-30 00:00:00
>>>>>"GGG","Pro duct Three (QAT6785)",1000 ,2003-09-01 00:00:00
>>>>>"HHH","Pro duct Three (QAT6785)",46.1 ,2003-08-04 00:00:00
>>>>>"III","Pro duct Three (QAT6785)",1000 ,2003-01-13 00:00:00
>>>>>"JJJ","Pro duct Three (QAT6785)",40.4 5,2003-08-04 00:00:00
>>>>>"JJJ","Pro duct Three (QAT6785)",40.4 5,2003-09-01 00:00:00
>>>>>"KKK","Pro duct Three (QAT6785)",44.7 5,2003-07-14 00:00:00
>>>>>"ZZZ","Pro duct Three (QAT556)",50.23 ,2003-01-13 00:00:00
>>>>>"AAA","Pro duct Three (QAT556)",1000, 2003-08-30 00:00:00
>>>>>"BBB","Pro duct Three (QAT556)",44.75 ,2003-07-22 00:00:00
>>>>>"BBB","Pro duct Three (QAT556)",532.2 5,2003-07-29 00:00:00
>>>>>"BBB","Pro duct Three (QAT556)",1000, 2003-07-30 00:00:00
>>>>>"BBB","Pro duct Three (QAT556)",1000, 2003-08-03 00:00:00
>>>>>"BBB","Pro duct Three (QAT556)",1000, 2003-08-04 00:00:00
>>>>>"BBB","Pro duct Three (QAT556)",44.75 ,2003-08-16 00:00:00
>>>>>"BBB","Pro duct Three (QAT556)",44.75 ,2003-08-27 00:00:00
>>>>>"CCC","Pro duct Three (QAT556)",1000, 2003-08-30 00:00:00
>>>>>"DDD","Pro duct Three (QAT556)",46.25 ,2003-05-08 00:00:00
>>>>>"EEE","Pro duct Three (QAT556)",1000, 2003-08-30 00:00:00
>>>>>"FFF","Pro duct Three (QAT556)",1000, 2003-08-30 00:00:00
>>>>>"GGG","Pro duct Three (QAT556)",1000, 2003-09-01 00:00:00
>>>>>"HHH","Pro duct Three (QAT556)",46.1, 2003-08-04 00:00:00
>>>>>"III","Pro duct Three (QAT556)",1000, 2003-01-13 00:00:00
>>>>>"JJJ","Pro duct Three (QAT556)",40.45 ,2003-08-04 00:00:00
>>>>>"JJJ","Pro duct Three (QAT556)",40.45 ,2003-09-01 00:00:00
>>>>>"KKK","Pro duct Three (QAT556)",44.75 ,2003-07-14 00:00:00
>>>>>"JJJ","Pro duct Three (QAT556)",40.15 ,2003-08-01 00:00:00[/color][/color][/color]

**netpurpose** · Jul 20 '05, 01:19 AM

Re: Need help with query

Hi Steve,

Thanks for your response. When I copied John's query, it works fine
and gives me the correct results. I did run both your query and his
against 330K of records, and it seems that his query runs much faster
(more than 10 times faster). I ran your query against clean products
names without the codes.

I am too novice to even know why the big difference. Both query
yields the same results. Can you tell why his statement is much more
efficient? LEFT OUTER JOIN vs EXISTS? I do want to learn from this.

Also, thanks for showing me the command to import the excel file to
db. Good to know :)

Thanks,
Netpurpose

Steve Kass <skass@drew.edu > wrote in message news:<xWV3b.326 8$Om1.1287@news read2.news.atl. earthlink.net>. ..[color=blue]
> Did I miscopy John's query? It gives me the future price of $25.04
> for Product One, but is easy to fix by adding
>
> AND P1.EffectiveDat e <= CURRENT_TIMESTA MP
>
> to the where clause of the derived table LatestPrices
>
> John's initial idea of NOT EXISTS still works, too, in part. (Note
> that I blew off the ProductName parsing by taking a hatchet to that
> column with an update...
>
>
> -- Be lazy
> UPDATE ProductList SET
> ProductName =
> SUBSTRING(Produ ctName, 1,CHARINDEX('(' , ProductName) - 2)
> GO
>
> -- For each product, select the lowest non-future
> -- price that has not been superseded.
> SELECT ProductName, MIN(Price) as Price -- get the lowest price
> FROM (
> SELECT ProductName, Price -- from all non-future prices
> FROM ProductList P1
> WHERE P1.EffectiveDat e <= CURRENT_TIMESTA MP
> AND NOT EXISTS ( -- that have not been superseded
> SELECT * FROM ProductList P2
> WHERE P2.Distributor = P1.Distributor
> AND P2.ProductName = P1.ProductName
> AND P2.EffectiveDat e <= CURRENT_TIMESTA MP
> AND P2.EffectiveDat e > P1.EffectiveDat e
> )
> ) T
> GROUP BY ProductName -- for each product
> go
>
> By the way, the delimited data was no trouble. I pasted it into
> Excel, did Text To Columns, named the data region, and inserted it with:
>
> insert into [ProductList]
> select Manufacturer, ProductName, Price, EffectiveDate
> from OpenRowset(
> 'Microsoft.Jet. OLEDB.4.0',
> 'Excel 8.0;Database=e: \excel\ProductL ist.xls',
> 'select * from ProductList')
>
> Be sure to close the Excel file before inserting.
>
> -- Steve Kass
> -- Drew University
> -- Ref: 2498EA13-1756-4C81-9307-25AFD5BB451D
>
>
>
> netpurpose wrote:[color=green]
> > Hi Jag,
> >
> > Thanks a lot!! It works like a charm! Your query saves me a lot of headache.
> >
> > I have struggled with this for quite a while now and I am glad I find help here.
> >
> > Again, thank you very much! I really appreciate your help in such a short time!
> >
> > Regards,
> > Netpurpose
> >
> >
> > "John Gilson" <jag@acm.org> wrote in message news:<amO3b.521 63$ev.12155054@ twister.nyc.rr. com>...
> >[color=darkred]
> >>"netpurpose " <netpurpose@hot mail.com> wrote in message
> >>news:31c57b38 .0308291024.6bd 2a29c@posting.g oogle.com...
> >>
> >>>Hi Jag,
> >>>
> >>>Thank you for your response. I tried the query, but it gives me a
> >>>different pricing result:
> >>>
> >>>ProductNam e Price
> >>>---------------------------------------- ---------------------
> >>>Product One (MXT234) 28.1500
> >>>Product Two (DGT6789) 44.3500
> >>>Product Three (QAT556) 40.1500
> >>>
> >>>The correct result should be:
> >>>
> >>>ProductNam e Price
> >>>---------------------------------------- ---------------------
> >>>Product One 33.5000
> >>>Product Two 44.7500
> >>>Product Three 40.4500
> >>>
> >>>The reason is because for Product One, Manufacturer "BBB" has a price
> >>>of 28.15 on 2003-07-30, this price is no longer valid because "BBB"
> >>>has more recent price of 33.5 starting on 2003-08-27. Same case with
> >>>Product Two and Three (manufacturer "JJJ" overrides the 40.15 on
> >>>2003-08-01 with 40.45 on 2003-08-04).
> >>>
> >>>I have to take the most recent prices from each manufacturer for a
> >>>particular product (price at the latest date as of today), and then
> >>>take the minimum price from the result.
> >>>
> >>>Again, thank you for your help. Sorry I might not explain it well in
> >>>the beginning. Any further help is appreciated. Thank you very much
> >>>in advance!
> >>>
> >>>Regards,
> >>>Netpurpose
> >>
> >>I was a little too quick on the draw and misread your requirements.
> >>
> >>SELECT ProductName, MIN(Price)
> >>FROM (SELECT P1.Distributor,
> >> SUBSTRING(P1.Pr oductName, 1,
> >> CHARINDEX('(', P1.ProductName) - 2) AS
> >> ProductName,
> >> P1.EffectiveDat e AS LatestDate,
> >> P1.price
> >> FROM ProductList AS P1
> >> LEFT OUTER JOIN
> >> ProductList AS P2
> >> ON P1.Distributor = P2.Distributor AND
> >> P1.ProductName = P2.ProductName AND
> >> P1.EffectiveDat e <= CURRENT_TIMESTA MP AND
> >> P2.EffectiveDat e <= CURRENT_TIMESTA MP AND
> >> P2.EffectiveDat e > P1.EffectiveDat e
> >> WHERE P2.EffectiveDat e IS NULL) AS LatestPrices
> >>GROUP BY ProductName
> >>
> >>Regards,
> >>jag
> >>
> >>
> >>>"John Gilson" <jag@acm.org> wrote in message news:<_uI3b.514 41$ev.11935402@ twister.nyc.rr. com>...
> >>>
> >>>>"netpurpose " <netpurpose@hot mail.com> wrote in message
> >>>>news:31c57b 38.0308290040.6 a560bd6@posting .google.com...
> >>>>
> >>>>>I need to extract data from this table to find the lowest prices of
> >>>>>each product as of today. The product will be listed/grouped by the
> >>>>>name only, discarding the product code - I use SUBSTRING(Produ ctName,
> >>>>>1, CHARINDEX('(', ProductName)-2).
> >>>>>
> >>>>>I can get this result, but I had to use several views (totally
> >>>>>inefficien t). I think this can be done in one efficient/fast query,
> >>>>>but I can't think of one.
> >>>>>
> >>>>>In the case that one query is not possible, is there other efficient
> >>>>>way to get the results? There are about 300K records in the table.
> >>>>>
> >>>>>Any help is appreciated! Thanks a lot in advance!
> >>>>>
> >>>>>Thanks,
> >>>>>Netpurpo se
> >>>>
> >>>>SELECT P1.ProductName, P1.Price
> >>>>FROM ProductList AS P1
> >>>>WHERE EffectiveDate <= CURRENT_TIMESTA MP AND
> >>>> NOT EXISTS
> >>>> (SELECT *
> >>>> FROM ProductList AS P2
> >>>> WHERE SUBSTRING(P1.Pr oductName, 1,
> >>>> CHARINDEX('(', P1.ProductName) - 2) =
> >>>> SUBSTRING(P2.Pr oductName, 1,
> >>>> CHARINDEX('(', P2.ProductName) - 2) AND
> >>>> P2.EffectiveDat e <= CURRENT_TIMESTA MP AND
> >>>> P2.Price < P1.Price)
> >>>>
> >>>>Regards,
> >>>>jag
> >>>>
> >>>>[/color][/color][/color]

**Steve Kass** · Jul 20 '05, 01:19 AM

Re: Need help with query

When I ran John's query on your sample data, It
returned the price of $25.04 for Product One, a price
that was not effective on the day I ran the query.

Make sure your sample data has some examples where
the lowest price is a future price that has been
recorded but is not yet effective.

As far as efficiency goes, all I did was look at query
plans. What I found was that John's query and mine
had virtually identical plans.

What I did was this:

Removed the part of product name in parentheses. If that data
is important, it should be a separate column. I removed it,
since to make this efficient there needed (I think) to be an
index with the ProductName value you want in the output, without
the extra comment, as the first column.

Removed all cases where the same (ProductName, Distributor,
EffectiveDate) appeared in more than one row (these probably
appeared when I removed the extra part of the product name).

Declared (ProductName, Distributor, EffectiveDate) to be the
primary key. Maybe I missed something and this does not work
as a key, but it seemed like a good choice for an index to
make the query fast. If it's not a key, add price as
a fourth column.

I realized now that there was extra nesting in my query.
I don't think it should have slowed it down tenfold, but the
outer two selects can be combined (if the data has no duplicates
in my key columns).

-- Select the lowest price
SELECT ProductName, MIN(Price)

-- from the table
FROM ProductList P1

-- that is not a future price
WHERE P1.EffectiveDat e <= CURRENT_TIMESTA MP

-- and that has not been superseded
AND NOT EXISTS (
-- by another price
SELECT * FROM ProductList P2
-- from the same distributor
WHERE P2.Distributor = P1.Distributor
-- for the same product
AND P2.ProductName = P1.ProductName
-- which other price has gone into effect
AND P2.EffectiveDat e <= CURRENT_TIMESTA MP
-- more recently
AND P2.EffectiveDat e > P1.EffectiveDat e
)

-- for each product
GROUP BY ProductName

Steve

netpurpose wrote:[color=blue]
> Hi Steve,
>
> Thanks for your response. When I copied John's query, it works fine
> and gives me the correct results. I did run both your query and his
> against 330K of records, and it seems that his query runs much faster
> (more than 10 times faster). I ran your query against clean products
> names without the codes.
>
> I am too novice to even know why the big difference. Both query
> yields the same results. Can you tell why his statement is much more
> efficient? LEFT OUTER JOIN vs EXISTS? I do want to learn from this.
>
> Also, thanks for showing me the command to import the excel file to
> db. Good to know :)
>
> Thanks,
> Netpurpose
>
> Steve Kass <skass@drew.edu > wrote in message news:<xWV3b.326 8$Om1.1287@news read2.news.atl. earthlink.net>. ..
>[color=green]
>>Did I miscopy John's query? It gives me the future price of $25.04
>>for Product One, but is easy to fix by adding
>>
>> AND P1.EffectiveDat e <= CURRENT_TIMESTA MP
>>
>>to the where clause of the derived table LatestPrices
>>
>>John's initial idea of NOT EXISTS still works, too, in part. (Note
>>that I blew off the ProductName parsing by taking a hatchet to that
>>column with an update...
>>
>>
>>-- Be lazy
>>UPDATE ProductList SET
>> ProductName =
>> SUBSTRING(Produ ctName, 1,CHARINDEX('(' , ProductName) - 2)
>>GO
>>
>>-- For each product, select the lowest non-future
>>-- price that has not been superseded.
>>SELECT ProductName, MIN(Price) as Price -- get the lowest price
>>FROM (
>> SELECT ProductName, Price -- from all non-future prices
>> FROM ProductList P1
>> WHERE P1.EffectiveDat e <= CURRENT_TIMESTA MP
>> AND NOT EXISTS ( -- that have not been superseded
>> SELECT * FROM ProductList P2
>> WHERE P2.Distributor = P1.Distributor
>> AND P2.ProductName = P1.ProductName
>> AND P2.EffectiveDat e <= CURRENT_TIMESTA MP
>> AND P2.EffectiveDat e > P1.EffectiveDat e
>> )
>>) T
>>GROUP BY ProductName -- for each product
>>go
>>
>>By the way, the delimited data was no trouble. I pasted it into
>>Excel, did Text To Columns, named the data region, and inserted it with:
>>
>>insert into [ProductList]
>>select Manufacturer, ProductName, Price, EffectiveDate
>>from OpenRowset(
>> 'Microsoft.Jet. OLEDB.4.0',
>> 'Excel 8.0;Database=e: \excel\ProductL ist.xls',
>> 'select * from ProductList')
>>
>>Be sure to close the Excel file before inserting.
>>
>>-- Steve Kass
>>-- Drew University
>>-- Ref: 2498EA13-1756-4C81-9307-25AFD5BB451D
>>
>>
>>
>>netpurpose wrote:
>>[color=darkred]
>>>Hi Jag,
>>>
>>>Thanks a lot!! It works like a charm! Your query saves me a lot of headache.
>>>
>>>I have struggled with this for quite a while now and I am glad I find help here.
>>>
>>>Again, thank you very much! I really appreciate your help in such a short time!
>>>
>>>Regards,
>>>Netpurpose
>>>
>>>
>>>"John Gilson" <jag@acm.org> wrote in message news:<amO3b.521 63$ev.12155054@ twister.nyc.rr. com>...
>>>
>>>
>>>>"netpurpose " <netpurpose@hot mail.com> wrote in message
>>>>news:31c57b 38.0308291024.6 bd2a29c@posting .google.com...
>>>>
>>>>
>>>>>Hi Jag,
>>>>>
>>>>>Thank you for your response. I tried the query, but it gives me a
>>>>>differen t pricing result:
>>>>>
>>>>>ProductNam e Price
>>>>>---------------------------------------- ---------------------
>>>>>Product One (MXT234) 28.1500
>>>>>Product Two (DGT6789) 44.3500
>>>>>Product Three (QAT556) 40.1500
>>>>>
>>>>>The correct result should be:
>>>>>
>>>>>ProductNam e Price
>>>>>---------------------------------------- ---------------------
>>>>>Product One 33.5000
>>>>>Product Two 44.7500
>>>>>Product Three 40.4500
>>>>>
>>>>>The reason is because for Product One, Manufacturer "BBB" has a price
>>>>>of 28.15 on 2003-07-30, this price is no longer valid because "BBB"
>>>>>has more recent price of 33.5 starting on 2003-08-27. Same case with
>>>>>Product Two and Three (manufacturer "JJJ" overrides the 40.15 on
>>>>>2003-08-01 with 40.45 on 2003-08-04).
>>>>>
>>>>>I have to take the most recent prices from each manufacturer for a
>>>>>particul ar product (price at the latest date as of today), and then
>>>>>take the minimum price from the result.
>>>>>
>>>>>Again, thank you for your help. Sorry I might not explain it well in
>>>>>the beginning. Any further help is appreciated. Thank you very much
>>>>>in advance!
>>>>>
>>>>>Regards,
>>>>>Netpurpo se
>>>>
>>>>I was a little too quick on the draw and misread your requirements.
>>>>
>>>>SELECT ProductName, MIN(Price)
>>>
>>>>FROM (SELECT P1.Distributor,
>>>
>>>> SUBSTRING(P1.Pr oductName, 1,
>>>> CHARINDEX('(', P1.ProductName) - 2) AS
>>>> ProductName,
>>>> P1.EffectiveDat e AS LatestDate,
>>>> P1.price
>>>> FROM ProductList AS P1
>>>> LEFT OUTER JOIN
>>>> ProductList AS P2
>>>> ON P1.Distributor = P2.Distributor AND
>>>> P1.ProductName = P2.ProductName AND
>>>> P1.EffectiveDat e <= CURRENT_TIMESTA MP AND
>>>> P2.EffectiveDat e <= CURRENT_TIMESTA MP AND
>>>> P2.EffectiveDat e > P1.EffectiveDat e
>>>> WHERE P2.EffectiveDat e IS NULL) AS LatestPrices
>>>>GROUP BY ProductName
>>>>
>>>>Regards,
>>>>jag
>>>>
>>>>
>>>>
>>>>>"John Gilson" <jag@acm.org> wrote in message news:<_uI3b.514 41$ev.11935402@ twister.nyc.rr. com>...
>>>>>
>>>>>
>>>>>>"netpurpo se" <netpurpose@hot mail.com> wrote in message
>>>>>>news:31c5 7b38.0308290040 .6a560bd6@posti ng.google.com.. .
>>>>>>
>>>>>>
>>>>>>>I need to extract data from this table to find the lowest prices of
>>>>>>>each product as of today. The product will be listed/grouped by the
>>>>>>>name only, discarding the product code - I use SUBSTRING(Produ ctName,
>>>>>>>1, CHARINDEX('(', ProductName)-2).
>>>>>>>
>>>>>>>I can get this result, but I had to use several views (totally
>>>>>>>ineffici ent). I think this can be done in one efficient/fast query,
>>>>>>>but I can't think of one.
>>>>>>>
>>>>>>>In the case that one query is not possible, is there other efficient
>>>>>>>way to get the results? There are about 300K records in the table.
>>>>>>>
>>>>>>>Any help is appreciated! Thanks a lot in advance!
>>>>>>>
>>>>>>>Thanks ,
>>>>>>>Netpurpo se
>>>>>>
>>>>>>SELECT P1.ProductName, P1.Price
>>>>>
>>>>>>FROM ProductList AS P1
>>>>>
>>>>>>WHERE EffectiveDate <= CURRENT_TIMESTA MP AND
>>>>>> NOT EXISTS
>>>>>> (SELECT *
>>>>>> FROM ProductList AS P2
>>>>>> WHERE SUBSTRING(P1.Pr oductName, 1,
>>>>>> CHARINDEX('(', P1.ProductName) - 2) =
>>>>>> SUBSTRING(P2.Pr oductName, 1,
>>>>>> CHARINDEX('(', P2.ProductName) - 2) AND
>>>>>> P2.EffectiveDat e <= CURRENT_TIMESTA MP AND
>>>>>> P2.Price < P1.Price)
>>>>>>
>>>>>>Regards ,
>>>>>>jag
>>>>>>
>>>>>>[/color][/color][/color]

**netpurpose** · Jul 20 '05, 01:20 AM

Re: Need help with query

Hi John and Steve,

Thank you very much for your help and the quick responses! I really
appreciate them.

Steve, thanks for explaining and commenting your query. I get a much
better understanding now.

John, I think in this last query, P2.EffectiveDat e <=
CURRENT_TIMESTA MP is missing from the OUTER JOIN. But as you
mentioned, it works fine when I just take the previous query and move
out the P1.EffectiveDat e <= CURRENT_TIMESTA MP. I didn't realize there
was a problem before because the live data as of yesterday has no
future pricing. Sorry, I should have tested it better.

Again, thanks to you both. The system works great and fast now!

Sincerely,
netpurpose

"John Gilson" <jag@acm.org> wrote in message news:<Q5m4b.601 19$ev.13564013@ twister.nyc.rr. com>...[color=blue]
> "Steve Kass" <skass@drew.edu > wrote in message
> news:u5f4b.9688 $Om1.4472@newsr ead2.news.atl.e arthlink.net...[color=green]
> > When I ran John's query on your sample data, It
> > returned the price of $25.04 for Product One, a price
> > that was not effective on the day I ran the query.
> >
> > Make sure your sample data has some examples where
> > the lowest price is a future price that has been
> > recorded but is not yet effective.[/color]
>
> Steve, you're absolutely right and stems from the (mis)placement
> of the selection criteria for the outer join. The constraint
> P1.EffectiveDat e <= CURRENT_TIMESTA MP
> should be applied *after* the outer join condition, that is, in the
> WHERE clause. So this should do the right thing:
>
> SELECT ProductName, MIN(Price)
> FROM (SELECT P1.Distributor,
> SUBSTRING(P1.Pr oductName, 1,
> CHARINDEX('(', P1.ProductName) - 2) AS
> ProductName,
> P1.EffectiveDat e AS LatestDate,
> P1.price
> FROM ProductList AS P1
> LEFT OUTER JOIN
> ProductList AS P2
> ON P1.Distributor = P2.Distributor AND
> P1.ProductName = P2.ProductName AND[/color]
[color=blue]
> P2.EffectiveDat e > P1.EffectiveDat e
> WHERE P2.EffectiveDat e IS NULL AND
> P1.EffectiveDat e <= CURRENT_TIMESTA MP)
> AS LatestPrices
> GROUP BY ProductName
>
> Regards,
> jag
>[color=green]
> > As far as efficiency goes, all I did was look at query
> > plans. What I found was that John's query and mine
> > had virtually identical plans.
> >
> > What I did was this:
> >
> > Removed the part of product name in parentheses. If that data
> > is important, it should be a separate column. I removed it,
> > since to make this efficient there needed (I think) to be an
> > index with the ProductName value you want in the output, without
> > the extra comment, as the first column.
> >
> > Removed all cases where the same (ProductName, Distributor,
> > EffectiveDate) appeared in more than one row (these probably
> > appeared when I removed the extra part of the product name).
> >
> > Declared (ProductName, Distributor, EffectiveDate) to be the
> > primary key. Maybe I missed something and this does not work
> > as a key, but it seemed like a good choice for an index to
> > make the query fast. If it's not a key, add price as
> > a fourth column.
> >
> > I realized now that there was extra nesting in my query.
> > I don't think it should have slowed it down tenfold, but the
> > outer two selects can be combined (if the data has no duplicates
> > in my key columns).
> >
> >
> > -- Select the lowest price
> > SELECT ProductName, MIN(Price)
> >
> > -- from the table
> > FROM ProductList P1
> >
> > -- that is not a future price
> > WHERE P1.EffectiveDat e <= CURRENT_TIMESTA MP
> >
> > -- and that has not been superseded
> > AND NOT EXISTS (
> > -- by another price
> > SELECT * FROM ProductList P2
> > -- from the same distributor
> > WHERE P2.Distributor = P1.Distributor
> > -- for the same product
> > AND P2.ProductName = P1.ProductName
> > -- which other price has gone into effect
> > AND P2.EffectiveDat e <= CURRENT_TIMESTA MP
> > -- more recently
> > AND P2.EffectiveDat e > P1.EffectiveDat e
> > )
> >
> > -- for each product
> > GROUP BY ProductName
> >
> > Steve
> >
> >
> > netpurpose wrote:[color=darkred]
> > > Hi Steve,
> > >
> > > Thanks for your response. When I copied John's query, it works fine
> > > and gives me the correct results. I did run both your query and his
> > > against 330K of records, and it seems that his query runs much faster
> > > (more than 10 times faster). I ran your query against clean products
> > > names without the codes.
> > >
> > > I am too novice to even know why the big difference. Both query
> > > yields the same results. Can you tell why his statement is much more
> > > efficient? LEFT OUTER JOIN vs EXISTS? I do want to learn from this.
> > >
> > > Also, thanks for showing me the command to import the excel file to
> > > db. Good to know :)
> > >
> > > Thanks,
> > > Netpurpose
> > >
> > > Steve Kass <skass@drew.edu > wrote in message[/color][/color]
> news:<xWV3b.326 8$Om1.1287@news read2.news.atl. earthlink.net>. ..[color=green][color=darkred]
> > >
> > >>Did I miscopy John's query? It gives me the future price of $25.04
> > >>for Product One, but is easy to fix by adding
> > >>
> > >> AND P1.EffectiveDat e <= CURRENT_TIMESTA MP
> > >>
> > >>to the where clause of the derived table LatestPrices
> > >>
> > >>John's initial idea of NOT EXISTS still works, too, in part. (Note
> > >>that I blew off the ProductName parsing by taking a hatchet to that
> > >>column with an update...
> > >>
> > >>
> > >>-- Be lazy
> > >>UPDATE ProductList SET
> > >> ProductName =
> > >> SUBSTRING(Produ ctName, 1,CHARINDEX('(' , ProductName) - 2)
> > >>GO
> > >>
> > >>-- For each product, select the lowest non-future
> > >>-- price that has not been superseded.
> > >>SELECT ProductName, MIN(Price) as Price -- get the lowest price
> > >>FROM (
> > >> SELECT ProductName, Price -- from all non-future prices
> > >> FROM ProductList P1
> > >> WHERE P1.EffectiveDat e <= CURRENT_TIMESTA MP
> > >> AND NOT EXISTS ( -- that have not been superseded
> > >> SELECT * FROM ProductList P2
> > >> WHERE P2.Distributor = P1.Distributor
> > >> AND P2.ProductName = P1.ProductName
> > >> AND P2.EffectiveDat e <= CURRENT_TIMESTA MP
> > >> AND P2.EffectiveDat e > P1.EffectiveDat e
> > >> )
> > >>) T
> > >>GROUP BY ProductName -- for each product
> > >>go
> > >>
> > >>By the way, the delimited data was no trouble. I pasted it into
> > >>Excel, did Text To Columns, named the data region, and inserted it with:
> > >>
> > >>insert into [ProductList]
> > >>select Manufacturer, ProductName, Price, EffectiveDate
> > >>from OpenRowset(
> > >> 'Microsoft.Jet. OLEDB.4.0',
> > >> 'Excel 8.0;Database=e: \excel\ProductL ist.xls',
> > >> 'select * from ProductList')
> > >>
> > >>Be sure to close the Excel file before inserting.
> > >>
> > >>-- Steve Kass
> > >>-- Drew University
> > >>-- Ref: 2498EA13-1756-4C81-9307-25AFD5BB451D
> > >>
> > >>
> > >>
> > >>netpurpose wrote:
> > >>
> > >>>Hi Jag,
> > >>>
> > >>>Thanks a lot!! It works like a charm! Your query saves me a lot of headache.
> > >>>
> > >>>I have struggled with this for quite a while now and I am glad I find help here.
> > >>>
> > >>>Again, thank you very much! I really appreciate your help in such a short time!
> > >>>
> > >>>Regards,
> > >>>Netpurpose
> > >>>
> > >>>
> > >>>"John Gilson" <jag@acm.org> wrote in message[/color][/color]
> news:<amO3b.521 63$ev.12155054@ twister.nyc.rr. com>...[color=green][color=darkred]
> > >>>
> > >>>
> > >>>>"netpurpose " <netpurpose@hot mail.com> wrote in message
> > >>>>news:31c57b 38.0308291024.6 bd2a29c@posting .google.com...
> > >>>>
> > >>>>
> > >>>>>Hi Jag,
> > >>>>>
> > >>>>>Thank you for your response. I tried the query, but it gives me a
> > >>>>>differen t pricing result:
> > >>>>>
> > >>>>>ProductNam e Price
> > >>>>>---------------------------------------- ---------------------
> > >>>>>Product One (MXT234) 28.1500
> > >>>>>Product Two (DGT6789) 44.3500
> > >>>>>Product Three (QAT556) 40.1500
> > >>>>>
> > >>>>>The correct result should be:
> > >>>>>
> > >>>>>ProductNam e Price
> > >>>>>---------------------------------------- ---------------------
> > >>>>>Product One 33.5000
> > >>>>>Product Two 44.7500
> > >>>>>Product Three 40.4500
> > >>>>>
> > >>>>>The reason is because for Product One, Manufacturer "BBB" has a price
> > >>>>>of 28.15 on 2003-07-30, this price is no longer valid because "BBB"
> > >>>>>has more recent price of 33.5 starting on 2003-08-27. Same case with
> > >>>>>Product Two and Three (manufacturer "JJJ" overrides the 40.15 on
> > >>>>>2003-08-01 with 40.45 on 2003-08-04).
> > >>>>>
> > >>>>>I have to take the most recent prices from each manufacturer for a
> > >>>>>particul ar product (price at the latest date as of today), and then
> > >>>>>take the minimum price from the result.
> > >>>>>
> > >>>>>Again, thank you for your help. Sorry I might not explain it well in
> > >>>>>the beginning. Any further help is appreciated. Thank you very much
> > >>>>>in advance!
> > >>>>>
> > >>>>>Regards,
> > >>>>>Netpurpo se
> > >>>>
> > >>>>I was a little too quick on the draw and misread your requirements.
> > >>>>
> > >>>>SELECT ProductName, MIN(Price)[/color][/color]
>[color=green][color=darkred]
> > >>>>FROM (SELECT P1.Distributor,[/color][/color]
>[color=green][color=darkred]
> > >>>> SUBSTRING(P1.Pr oductName, 1,
> > >>>> CHARINDEX('(', P1.ProductName) - 2) AS
> > >>>> ProductName,
> > >>>> P1.EffectiveDat e AS LatestDate,
> > >>>> P1.price
> > >>>> FROM ProductList AS P1
> > >>>> LEFT OUTER JOIN
> > >>>> ProductList AS P2
> > >>>> ON P1.Distributor = P2.Distributor AND
> > >>>> P1.ProductName = P2.ProductName AND
> > >>>> P1.EffectiveDat e <= CURRENT_TIMESTA MP AND
> > >>>> P2.EffectiveDat e <= CURRENT_TIMESTA MP AND
> > >>>> P2.EffectiveDat e > P1.EffectiveDat e
> > >>>> WHERE P2.EffectiveDat e IS NULL) AS LatestPrices
> > >>>>GROUP BY ProductName
> > >>>>
> > >>>>Regards,
> > >>>>jag
> > >>>>
> > >>>>
> > >>>>
> > >>>>>"John Gilson" <jag@acm.org> wrote in message[/color][/color]
> news:<_uI3b.514 41$ev.11935402@ twister.nyc.rr. com>...[color=green][color=darkred]
> > >>>>>
> > >>>>>
> > >>>>>>"netpurpo se" <netpurpose@hot mail.com> wrote in message
> > >>>>>>news:31c5 7b38.0308290040 .6a560bd6@posti ng.google.com.. .
> > >>>>>>
> > >>>>>>
> > >>>>>>>I need to extract data from this table to find the lowest prices of
> > >>>>>>>each product as of today. The product will be listed/grouped by the
> > >>>>>>>name only, discarding the product code - I use SUBSTRING(Produ ctName,
> > >>>>>>>1, CHARINDEX('(', ProductName)-2).
> > >>>>>>>
> > >>>>>>>I can get this result, but I had to use several views (totally
> > >>>>>>>ineffici ent). I think this can be done in one efficient/fast query,
> > >>>>>>>but I can't think of one.
> > >>>>>>>
> > >>>>>>>In the case that one query is not possible, is there other efficient
> > >>>>>>>way to get the results? There are about 300K records in the table.
> > >>>>>>>
> > >>>>>>>Any help is appreciated! Thanks a lot in advance!
> > >>>>>>>
> > >>>>>>>Thanks ,
> > >>>>>>>Netpurpo se
> > >>>>>>
> > >>>>>>SELECT P1.ProductName, P1.Price[/color][/color]
>[color=green][color=darkred]
> > >>>>>>FROM ProductList AS P1[/color][/color]
>[color=green][color=darkred]
> > >>>>>>WHERE EffectiveDate <= CURRENT_TIMESTA MP AND
> > >>>>>> NOT EXISTS
> > >>>>>> (SELECT *
> > >>>>>> FROM ProductList AS P2
> > >>>>>> WHERE SUBSTRING(P1.Pr oductName, 1,
> > >>>>>> CHARINDEX('(', P1.ProductName) - 2) =
> > >>>>>> SUBSTRING(P2.Pr oductName, 1,
> > >>>>>> CHARINDEX('(', P2.ProductName) - 2)[/color][/color]
> AND[color=green][color=darkred]
> > >>>>>> P2.EffectiveDat e <= CURRENT_TIMESTA MP AND
> > >>>>>> P2.Price < P1.Price)
> > >>>>>>
> > >>>>>>Regards ,
> > >>>>>>jag
> > >>>>>>
> > >>>>>>[/color]
> >[/color][/color]

**Steve Kass** · Jul 20 '05, 01:20 AM

Re: Need help with query

John,

I hate to be a pest, but I believe you need the
date restriction in two places. The query here will
fail if the lowest price for a product comes from a
distributor that has already announced a price to become
effective in the future. If that is true, the future
price will come up on the right side of the join, since
there is no date restriction there. That makes the value
of P2.EffectiveDat e not null and in the future, and the
P1.Price in that row, despite being the lowest for the
product, is filtered out.

Ok, I lied - I don't hate being a pest, but I do
think your query doesn't quite work.

Steve

John Gilson wrote:[color=blue]
> "Steve Kass" <skass@drew.edu > wrote in message
> news:u5f4b.9688 $Om1.4472@newsr ead2.news.atl.e arthlink.net...
>[color=green]
>>When I ran John's query on your sample data, It
>>returned the price of $25.04 for Product One, a price
>>that was not effective on the day I ran the query.
>>
>>Make sure your sample data has some examples where
>>the lowest price is a future price that has been
>>recorded but is not yet effective.[/color]
>
>
> Steve, you're absolutely right and stems from the (mis)placement
> of the selection criteria for the outer join. The constraint
> P1.EffectiveDat e <= CURRENT_TIMESTA MP
> should be applied *after* the outer join condition, that is, in the
> WHERE clause. So this should do the right thing:
>
> SELECT ProductName, MIN(Price)
> FROM (SELECT P1.Distributor,
> SUBSTRING(P1.Pr oductName, 1,
> CHARINDEX('(', P1.ProductName) - 2) AS
> ProductName,
> P1.EffectiveDat e AS LatestDate,
> P1.price
> FROM ProductList AS P1
> LEFT OUTER JOIN
> ProductList AS P2
> ON P1.Distributor = P2.Distributor AND
> P1.ProductName = P2.ProductName AND
> P2.EffectiveDat e > P1.EffectiveDat e
> WHERE P2.EffectiveDat e IS NULL AND
> P1.EffectiveDat e <= CURRENT_TIMESTA MP)
> AS LatestPrices
> GROUP BY ProductName
>
> Regards,
> jag
>
>[color=green]
>>As far as efficiency goes, all I did was look at query
>>plans. What I found was that John's query and mine
>>had virtually identical plans.
>>
>>What I did was this:
>>
>> Removed the part of product name in parentheses. If that data
>>is important, it should be a separate column. I removed it,
>>since to make this efficient there needed (I think) to be an
>>index with the ProductName value you want in the output, without
>>the extra comment, as the first column.
>>
>> Removed all cases where the same (ProductName, Distributor,
>>EffectiveDate ) appeared in more than one row (these probably
>>appeared when I removed the extra part of the product name).
>>
>> Declared (ProductName, Distributor, EffectiveDate) to be the
>>primary key. Maybe I missed something and this does not work
>>as a key, but it seemed like a good choice for an index to
>>make the query fast. If it's not a key, add price as
>>a fourth column.
>>
>> I realized now that there was extra nesting in my query.
>>I don't think it should have slowed it down tenfold, but the
>>outer two selects can be combined (if the data has no duplicates
>>in my key columns).
>>
>>
>>-- Select the lowest price
>>SELECT ProductName, MIN(Price)
>>
>>-- from the table
>>FROM ProductList P1
>>
>>-- that is not a future price
>>WHERE P1.EffectiveDat e <= CURRENT_TIMESTA MP
>>
>>-- and that has not been superseded
>>AND NOT EXISTS (
>> -- by another price
>> SELECT * FROM ProductList P2
>> -- from the same distributor
>> WHERE P2.Distributor = P1.Distributor
>> -- for the same product
>> AND P2.ProductName = P1.ProductName
>> -- which other price has gone into effect
>> AND P2.EffectiveDat e <= CURRENT_TIMESTA MP
>> -- more recently
>> AND P2.EffectiveDat e > P1.EffectiveDat e
>>)
>>
>>-- for each product
>>GROUP BY ProductName
>>
>>Steve
>>
>>
>>netpurpose wrote:
>>[color=darkred]
>>>Hi Steve,
>>>
>>>Thanks for your response. When I copied John's query, it works fine
>>>and gives me the correct results. I did run both your query and his
>>>against 330K of records, and it seems that his query runs much faster
>>>(more than 10 times faster). I ran your query against clean products
>>>names without the codes.
>>>
>>>I am too novice to even know why the big difference. Both query
>>>yields the same results. Can you tell why his statement is much more
>>>efficient? LEFT OUTER JOIN vs EXISTS? I do want to learn from this.
>>>
>>>Also, thanks for showing me the command to import the excel file to
>>>db. Good to know :)
>>>
>>>Thanks,
>>>Netpurpose
>>>
>>>Steve Kass <skass@drew.edu > wrote in message[/color][/color]
>
> news:<xWV3b.326 8$Om1.1287@news read2.news.atl. earthlink.net>. ..
>[color=green][color=darkred]
>>>>Did I miscopy John's query? It gives me the future price of $25.04
>>>>for Product One, but is easy to fix by adding
>>>>
>>>> AND P1.EffectiveDat e <= CURRENT_TIMESTA MP
>>>>
>>>>to the where clause of the derived table LatestPrices
>>>>
>>>>John's initial idea of NOT EXISTS still works, too, in part. (Note
>>>>that I blew off the ProductName parsing by taking a hatchet to that
>>>>column with an update...
>>>>
>>>>
>>>>-- Be lazy
>>>>UPDATE ProductList SET
>>>> ProductName =
>>>> SUBSTRING(Produ ctName, 1,CHARINDEX('(' , ProductName) - 2)
>>>>GO
>>>>
>>>>-- For each product, select the lowest non-future
>>>>-- price that has not been superseded.
>>>>SELECT ProductName, MIN(Price) as Price -- get the lowest price
>>>
>>>>FROM (
>>>
>>>> SELECT ProductName, Price -- from all non-future prices
>>>> FROM ProductList P1
>>>> WHERE P1.EffectiveDat e <= CURRENT_TIMESTA MP
>>>> AND NOT EXISTS ( -- that have not been superseded
>>>> SELECT * FROM ProductList P2
>>>> WHERE P2.Distributor = P1.Distributor
>>>> AND P2.ProductName = P1.ProductName
>>>> AND P2.EffectiveDat e <= CURRENT_TIMESTA MP
>>>> AND P2.EffectiveDat e > P1.EffectiveDat e
>>>> )
>>>>) T
>>>>GROUP BY ProductName -- for each product
>>>>go
>>>>
>>>>By the way, the delimited data was no trouble. I pasted it into
>>>>Excel, did Text To Columns, named the data region, and inserted it with:
>>>>
>>>>insert into [ProductList]
>>>>select Manufacturer, ProductName, Price, EffectiveDate
>>>
>>>>from OpenRowset(
>>>
>>>> 'Microsoft.Jet. OLEDB.4.0',
>>>> 'Excel 8.0;Database=e: \excel\ProductL ist.xls',
>>>> 'select * from ProductList')
>>>>
>>>>Be sure to close the Excel file before inserting.
>>>>
>>>>-- Steve Kass
>>>>-- Drew University
>>>>-- Ref: 2498EA13-1756-4C81-9307-25AFD5BB451D
>>>>
>>>>
>>>>
>>>>netpurpos e wrote:
>>>>
>>>>
>>>>>Hi Jag,
>>>>>
>>>>>Thanks a lot!! It works like a charm! Your query saves me a lot of headache.
>>>>>
>>>>>I have struggled with this for quite a while now and I am glad I find help here.
>>>>>
>>>>>Again, thank you very much! I really appreciate your help in such a short time!
>>>>>
>>>>>Regards,
>>>>>Netpurpo se
>>>>>
>>>>>
>>>>>"John Gilson" <jag@acm.org> wrote in message[/color][/color]
>
> news:<amO3b.521 63$ev.12155054@ twister.nyc.rr. com>...
>[color=green][color=darkred]
>>>>>
>>>>>>"netpurpo se" <netpurpose@hot mail.com> wrote in message
>>>>>>news:31c5 7b38.0308291024 .6bd2a29c@posti ng.google.com.. .
>>>>>>
>>>>>>
>>>>>>
>>>>>>>Hi Jag,
>>>>>>>
>>>>>>>Thank you for your response. I tried the query, but it gives me a
>>>>>>>differen t pricing result:
>>>>>>>
>>>>>>>ProductN ame Price
>>>>>>>---------------------------------------- ---------------------
>>>>>>>Produc t One (MXT234) 28.1500
>>>>>>>Produc t Two (DGT6789) 44.3500
>>>>>>>Produc t Three (QAT556) 40.1500
>>>>>>>
>>>>>>>The correct result should be:
>>>>>>>
>>>>>>>ProductN ame Price
>>>>>>>---------------------------------------- ---------------------
>>>>>>>Produc t One 33.5000
>>>>>>>Produc t Two 44.7500
>>>>>>>Produc t Three 40.4500
>>>>>>>
>>>>>>>The reason is because for Product One, Manufacturer "BBB" has a price
>>>>>>>of 28.15 on 2003-07-30, this price is no longer valid because "BBB"
>>>>>>>has more recent price of 33.5 starting on 2003-08-27. Same case with
>>>>>>>Produc t Two and Three (manufacturer "JJJ" overrides the 40.15 on
>>>>>>>2003-08-01 with 40.45 on 2003-08-04).
>>>>>>>
>>>>>>>I have to take the most recent prices from each manufacturer for a
>>>>>>>particul ar product (price at the latest date as of today), and then
>>>>>>>take the minimum price from the result.
>>>>>>>
>>>>>>>Again, thank you for your help. Sorry I might not explain it well in
>>>>>>>the beginning. Any further help is appreciated. Thank you very much
>>>>>>>in advance!
>>>>>>>
>>>>>>>Regard s,
>>>>>>>Netpurpo se
>>>>>>
>>>>>>I was a little too quick on the draw and misread your requirements.
>>>>>>
>>>>>>SELECT ProductName, MIN(Price)
>>>>>
>>>>>>FROM (SELECT P1.Distributor,
>>>>>
>>>>>
>>>>>> SUBSTRING(P1.Pr oductName, 1,
>>>>>> CHARINDEX('(', P1.ProductName) - 2) AS
>>>>>> ProductName,
>>>>>> P1.EffectiveDat e AS LatestDate,
>>>>>> P1.price
>>>>>> FROM ProductList AS P1
>>>>>> LEFT OUTER JOIN
>>>>>> ProductList AS P2
>>>>>> ON P1.Distributor = P2.Distributor AND
>>>>>> P1.ProductName = P2.ProductName AND
>>>>>> P1.EffectiveDat e <= CURRENT_TIMESTA MP AND
>>>>>> P2.EffectiveDat e <= CURRENT_TIMESTA MP AND
>>>>>> P2.EffectiveDat e > P1.EffectiveDat e
>>>>>> WHERE P2.EffectiveDat e IS NULL) AS LatestPrices
>>>>>>GROUP BY ProductName
>>>>>>
>>>>>>Regards ,
>>>>>>jag
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>"John Gilson" <jag@acm.org> wrote in message[/color][/color]
>
> news:<_uI3b.514 41$ev.11935402@ twister.nyc.rr. com>...
>[color=green][color=darkred]
>>>>>>>
>>>>>>>>"netpur pose" <netpurpose@hot mail.com> wrote in message
>>>>>>>>news:31 c57b38.03082900 40.6a560bd6@pos ting.google.com ...
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>>I need to extract data from this table to find the lowest prices of
>>>>>>>>>each product as of today. The product will be listed/grouped by the
>>>>>>>>>name only, discarding the product code - I use SUBSTRING(Produ ctName,
>>>>>>>>>1, CHARINDEX('(', ProductName)-2).
>>>>>>>>>
>>>>>>>>>I can get this result, but I had to use several views (totally
>>>>>>>>>ineffi cient). I think this can be done in one efficient/fast query,
>>>>>>>>>but I can't think of one.
>>>>>>>>>
>>>>>>>>>In the case that one query is not possible, is there other efficient
>>>>>>>>>way to get the results? There are about 300K records in the table.
>>>>>>>>>
>>>>>>>>>Any help is appreciated! Thanks a lot in advance!
>>>>>>>>>
>>>>>>>>>Thanks ,
>>>>>>>>>Netpur pose
>>>>>>>>
>>>>>>>>SELEC T P1.ProductName, P1.Price
>>>>>>>
>>>>>>>>FROM ProductList AS P1
>>>>>>>
>>>>>>>
>>>>>>>>WHERE EffectiveDate <= CURRENT_TIMESTA MP AND
>>>>>>>> NOT EXISTS
>>>>>>>> (SELECT *
>>>>>>>> FROM ProductList AS P2
>>>>>>>> WHERE SUBSTRING(P1.Pr oductName, 1,
>>>>>>>> CHARINDEX('(', P1.ProductName) - 2) =
>>>>>>>> SUBSTRING(P2.Pr oductName, 1,
>>>>>>>> CHARINDEX('(', P2.ProductName) - 2)[/color][/color]
>
> AND
>[color=green][color=darkred]
>>>>>>>> P2.EffectiveDat e <= CURRENT_TIMESTA MP AND
>>>>>>>> P2.Price < P1.Price)
>>>>>>>>
>>>>>>>>Regards ,
>>>>>>>>jag
>>>>>>>>
>>>>>>>>[/color]
>>[/color]
>
>[/color]

**John Gilson** · Jul 20 '05, 01:20 AM

Re: Need help with query

"Steve Kass" <skass@drew.edu > wrote in message
news:dGx4b.1367 4$Om1.5022@news read2.news.atl. earthlink.net.. .[color=blue]
> John,
>
> I hate to be a pest, but I believe you need the
> date restriction in two places. The query here will
> fail if the lowest price for a product comes from a
> distributor that has already announced a price to become
> effective in the future. If that is true, the future
> price will come up on the right side of the join, since
> there is no date restriction there. That makes the value
> of P2.EffectiveDat e not null and in the future, and the
> P1.Price in that row, despite being the lowest for the
> product, is filtered out.
>
> Ok, I lied - I don't hate being a pest, but I do
> think your query doesn't quite work.
>
> Steve[/color]

Steve, I don't hate you for being a pest. Ok, I lied - I do hate you
for being a pest but, of course, you happen to also be correct (again!)
so, to a small extent, it assuages your pestiferousness . But seriously,
in my haste, I seemed to have dropped a condition that I had originally
specified in the outer join, that is,
P2.EffectiveDat e <= CURRENT_TIMESTA MP
Putting this back in leaves us with

SELECT ProductName, MIN(Price) AS Price
FROM (SELECT P1.Distributor,
SUBSTRING(P1.Pr oductName, 1,
CHARINDEX('(', P1.ProductName) - 2) AS
ProductName,
P1.EffectiveDat e AS LatestDate,
P1.price
FROM ProductList AS P1
LEFT OUTER JOIN
ProductList AS P2
ON P1.Distributor = P2.Distributor AND
P1.ProductName = P2.ProductName AND
P2.EffectiveDat e > P1.EffectiveDat e AND
P2.EffectiveDat e <= CURRENT_TIMESTA MP
WHERE P2.EffectiveDat e IS NULL AND
P1.EffectiveDat e <= CURRENT_TIMESTA MP)
AS LatestPrices
GROUP BY ProductName

And Steve, thanks for the sharp eye and sharper mind.

Regards,
jag
[color=blue]
> John Gilson wrote:[color=green]
> > "Steve Kass" <skass@drew.edu > wrote in message
> > news:u5f4b.9688 $Om1.4472@newsr ead2.news.atl.e arthlink.net...
> >[color=darkred]
> >>When I ran John's query on your sample data, It
> >>returned the price of $25.04 for Product One, a price
> >>that was not effective on the day I ran the query.
> >>
> >>Make sure your sample data has some examples where
> >>the lowest price is a future price that has been
> >>recorded but is not yet effective.[/color]
> >
> >
> > Steve, you're absolutely right and stems from the (mis)placement
> > of the selection criteria for the outer join. The constraint
> > P1.EffectiveDat e <= CURRENT_TIMESTA MP
> > should be applied *after* the outer join condition, that is, in the
> > WHERE clause. So this should do the right thing:
> >
> > SELECT ProductName, MIN(Price)
> > FROM (SELECT P1.Distributor,
> > SUBSTRING(P1.Pr oductName, 1,
> > CHARINDEX('(', P1.ProductName) - 2) AS
> > ProductName,
> > P1.EffectiveDat e AS LatestDate,
> > P1.price
> > FROM ProductList AS P1
> > LEFT OUTER JOIN
> > ProductList AS P2
> > ON P1.Distributor = P2.Distributor AND
> > P1.ProductName = P2.ProductName AND
> > P2.EffectiveDat e > P1.EffectiveDat e
> > WHERE P2.EffectiveDat e IS NULL AND
> > P1.EffectiveDat e <= CURRENT_TIMESTA MP)
> > AS LatestPrices
> > GROUP BY ProductName
> >
> > Regards,
> > jag
> >
> >[color=darkred]
> >>As far as efficiency goes, all I did was look at query
> >>plans. What I found was that John's query and mine
> >>had virtually identical plans.
> >>
> >>What I did was this:
> >>
> >> Removed the part of product name in parentheses. If that data
> >>is important, it should be a separate column. I removed it,
> >>since to make this efficient there needed (I think) to be an
> >>index with the ProductName value you want in the output, without
> >>the extra comment, as the first column.
> >>
> >> Removed all cases where the same (ProductName, Distributor,
> >>EffectiveDate ) appeared in more than one row (these probably
> >>appeared when I removed the extra part of the product name).
> >>
> >> Declared (ProductName, Distributor, EffectiveDate) to be the
> >>primary key. Maybe I missed something and this does not work
> >>as a key, but it seemed like a good choice for an index to
> >>make the query fast. If it's not a key, add price as
> >>a fourth column.
> >>
> >> I realized now that there was extra nesting in my query.
> >>I don't think it should have slowed it down tenfold, but the
> >>outer two selects can be combined (if the data has no duplicates
> >>in my key columns).
> >>
> >>
> >>-- Select the lowest price
> >>SELECT ProductName, MIN(Price)
> >>
> >>-- from the table
> >>FROM ProductList P1
> >>
> >>-- that is not a future price
> >>WHERE P1.EffectiveDat e <= CURRENT_TIMESTA MP
> >>
> >>-- and that has not been superseded
> >>AND NOT EXISTS (
> >> -- by another price
> >> SELECT * FROM ProductList P2
> >> -- from the same distributor
> >> WHERE P2.Distributor = P1.Distributor
> >> -- for the same product
> >> AND P2.ProductName = P1.ProductName
> >> -- which other price has gone into effect
> >> AND P2.EffectiveDat e <= CURRENT_TIMESTA MP
> >> -- more recently
> >> AND P2.EffectiveDat e > P1.EffectiveDat e
> >>)
> >>
> >>-- for each product
> >>GROUP BY ProductName
> >>
> >>Steve
> >>
> >>
> >>netpurpose wrote:
> >>
> >>>Hi Steve,
> >>>
> >>>Thanks for your response. When I copied John's query, it works fine
> >>>and gives me the correct results. I did run both your query and his
> >>>against 330K of records, and it seems that his query runs much faster
> >>>(more than 10 times faster). I ran your query against clean products
> >>>names without the codes.
> >>>
> >>>I am too novice to even know why the big difference. Both query
> >>>yields the same results. Can you tell why his statement is much more
> >>>efficient? LEFT OUTER JOIN vs EXISTS? I do want to learn from this.
> >>>
> >>>Also, thanks for showing me the command to import the excel file to
> >>>db. Good to know :)
> >>>
> >>>Thanks,
> >>>Netpurpose
> >>>
> >>>Steve Kass <skass@drew.edu > wrote in message[/color]
> >
> > news:<xWV3b.326 8$Om1.1287@news read2.news.atl. earthlink.net>. ..
> >[color=darkred]
> >>>>Did I miscopy John's query? It gives me the future price of $25.04
> >>>>for Product One, but is easy to fix by adding
> >>>>
> >>>> AND P1.EffectiveDat e <= CURRENT_TIMESTA MP
> >>>>
> >>>>to the where clause of the derived table LatestPrices
> >>>>
> >>>>John's initial idea of NOT EXISTS still works, too, in part. (Note
> >>>>that I blew off the ProductName parsing by taking a hatchet to that
> >>>>column with an update...
> >>>>
> >>>>
> >>>>-- Be lazy
> >>>>UPDATE ProductList SET
> >>>> ProductName =
> >>>> SUBSTRING(Produ ctName, 1,CHARINDEX('(' , ProductName) - 2)
> >>>>GO
> >>>>
> >>>>-- For each product, select the lowest non-future
> >>>>-- price that has not been superseded.
> >>>>SELECT ProductName, MIN(Price) as Price -- get the lowest price
> >>>
> >>>>FROM (
> >>>
> >>>> SELECT ProductName, Price -- from all non-future prices
> >>>> FROM ProductList P1
> >>>> WHERE P1.EffectiveDat e <= CURRENT_TIMESTA MP
> >>>> AND NOT EXISTS ( -- that have not been superseded
> >>>> SELECT * FROM ProductList P2
> >>>> WHERE P2.Distributor = P1.Distributor
> >>>> AND P2.ProductName = P1.ProductName
> >>>> AND P2.EffectiveDat e <= CURRENT_TIMESTA MP
> >>>> AND P2.EffectiveDat e > P1.EffectiveDat e
> >>>> )
> >>>>) T
> >>>>GROUP BY ProductName -- for each product
> >>>>go
> >>>>
> >>>>By the way, the delimited data was no trouble. I pasted it into
> >>>>Excel, did Text To Columns, named the data region, and inserted it with:
> >>>>
> >>>>insert into [ProductList]
> >>>>select Manufacturer, ProductName, Price, EffectiveDate
> >>>
> >>>>from OpenRowset(
> >>>
> >>>> 'Microsoft.Jet. OLEDB.4.0',
> >>>> 'Excel 8.0;Database=e: \excel\ProductL ist.xls',
> >>>> 'select * from ProductList')
> >>>>
> >>>>Be sure to close the Excel file before inserting.
> >>>>
> >>>>-- Steve Kass
> >>>>-- Drew University
> >>>>-- Ref: 2498EA13-1756-4C81-9307-25AFD5BB451D
> >>>>
> >>>>
> >>>>
> >>>>netpurpos e wrote:
> >>>>
> >>>>
> >>>>>Hi Jag,
> >>>>>
> >>>>>Thanks a lot!! It works like a charm! Your query saves me a lot of headache.
> >>>>>
> >>>>>I have struggled with this for quite a while now and I am glad I find help here.
> >>>>>
> >>>>>Again, thank you very much! I really appreciate your help in such a short time!
> >>>>>
> >>>>>Regards,
> >>>>>Netpurpo se
> >>>>>
> >>>>>
> >>>>>"John Gilson" <jag@acm.org> wrote in message[/color]
> >
> > news:<amO3b.521 63$ev.12155054@ twister.nyc.rr. com>...
> >[color=darkred]
> >>>>>
> >>>>>>"netpurpo se" <netpurpose@hot mail.com> wrote in message
> >>>>>>news:31c5 7b38.0308291024 .6bd2a29c@posti ng.google.com.. .
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>>Hi Jag,
> >>>>>>>
> >>>>>>>Thank you for your response. I tried the query, but it gives me a
> >>>>>>>differen t pricing result:
> >>>>>>>
> >>>>>>>ProductN ame Price
> >>>>>>>---------------------------------------- ---------------------
> >>>>>>>Produc t One (MXT234) 28.1500
> >>>>>>>Produc t Two (DGT6789) 44.3500
> >>>>>>>Produc t Three (QAT556) 40.1500
> >>>>>>>
> >>>>>>>The correct result should be:
> >>>>>>>
> >>>>>>>ProductN ame Price
> >>>>>>>---------------------------------------- ---------------------
> >>>>>>>Produc t One 33.5000
> >>>>>>>Produc t Two 44.7500
> >>>>>>>Produc t Three 40.4500
> >>>>>>>
> >>>>>>>The reason is because for Product One, Manufacturer "BBB" has a price
> >>>>>>>of 28.15 on 2003-07-30, this price is no longer valid because "BBB"
> >>>>>>>has more recent price of 33.5 starting on 2003-08-27. Same case with
> >>>>>>>Produc t Two and Three (manufacturer "JJJ" overrides the 40.15 on
> >>>>>>>2003-08-01 with 40.45 on 2003-08-04).
> >>>>>>>
> >>>>>>>I have to take the most recent prices from each manufacturer for a
> >>>>>>>particul ar product (price at the latest date as of today), and then
> >>>>>>>take the minimum price from the result.
> >>>>>>>
> >>>>>>>Again, thank you for your help. Sorry I might not explain it well in
> >>>>>>>the beginning. Any further help is appreciated. Thank you very much
> >>>>>>>in advance!
> >>>>>>>
> >>>>>>>Regard s,
> >>>>>>>Netpurpo se
> >>>>>>
> >>>>>>I was a little too quick on the draw and misread your requirements.
> >>>>>>
> >>>>>>SELECT ProductName, MIN(Price)
> >>>>>
> >>>>>>FROM (SELECT P1.Distributor,
> >>>>>
> >>>>>
> >>>>>> SUBSTRING(P1.Pr oductName, 1,
> >>>>>> CHARINDEX('(', P1.ProductName) - 2) AS
> >>>>>> ProductName,
> >>>>>> P1.EffectiveDat e AS LatestDate,
> >>>>>> P1.price
> >>>>>> FROM ProductList AS P1
> >>>>>> LEFT OUTER JOIN
> >>>>>> ProductList AS P2
> >>>>>> ON P1.Distributor = P2.Distributor AND
> >>>>>> P1.ProductName = P2.ProductName AND
> >>>>>> P1.EffectiveDat e <= CURRENT_TIMESTA MP AND
> >>>>>> P2.EffectiveDat e <= CURRENT_TIMESTA MP AND
> >>>>>> P2.EffectiveDat e > P1.EffectiveDat e
> >>>>>> WHERE P2.EffectiveDat e IS NULL) AS LatestPrices
> >>>>>>GROUP BY ProductName
> >>>>>>
> >>>>>>Regards ,
> >>>>>>jag
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>>"John Gilson" <jag@acm.org> wrote in message[/color]
> >
> > news:<_uI3b.514 41$ev.11935402@ twister.nyc.rr. com>...
> >[color=darkred]
> >>>>>>>
> >>>>>>>>"netpur pose" <netpurpose@hot mail.com> wrote in message
> >>>>>>>>news:31 c57b38.03082900 40.6a560bd6@pos ting.google.com ...
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>>I need to extract data from this table to find the lowest prices of
> >>>>>>>>>each product as of today. The product will be listed/grouped by the
> >>>>>>>>>name only, discarding the product code - I use SUBSTRING(Produ ctName,
> >>>>>>>>>1, CHARINDEX('(', ProductName)-2).
> >>>>>>>>>
> >>>>>>>>>I can get this result, but I had to use several views (totally
> >>>>>>>>>ineffi cient). I think this can be done in one efficient/fast query,
> >>>>>>>>>but I can't think of one.
> >>>>>>>>>
> >>>>>>>>>In the case that one query is not possible, is there other efficient
> >>>>>>>>>way to get the results? There are about 300K records in the table.
> >>>>>>>>>
> >>>>>>>>>Any help is appreciated! Thanks a lot in advance!
> >>>>>>>>>
> >>>>>>>>>Thanks ,
> >>>>>>>>>Netpur pose
> >>>>>>>>
> >>>>>>>>SELEC T P1.ProductName, P1.Price
> >>>>>>>
> >>>>>>>>FROM ProductList AS P1
> >>>>>>>
> >>>>>>>
> >>>>>>>>WHERE EffectiveDate <= CURRENT_TIMESTA MP AND
> >>>>>>>> NOT EXISTS
> >>>>>>>> (SELECT *
> >>>>>>>> FROM ProductList AS P2
> >>>>>>>> WHERE SUBSTRING(P1.Pr oductName, 1,
> >>>>>>>> CHARINDEX('(', P1.ProductName) - 2) =
> >>>>>>>> SUBSTRING(P2.Pr oductName, 1,
> >>>>>>>> CHARINDEX('(', P2.ProductName) - 2)[/color]
> >
> > AND
> >[color=darkred]
> >>>>>>>> P2.EffectiveDat e <= CURRENT_TIMESTA MP AND
> >>>>>>>> P2.Price < P1.Price)
> >>>>>>>>
> >>>>>>>>Regards ,
> >>>>>>>>jag
> >>>>>>>>
> >>>>>>>>
> >>[/color]
> >
> >[/color]
>[/color]

**Steve Kass** · Jul 20 '05, 01:20 AM

Re: Need help with query

John Gilson wrote:[color=blue]
> "Steve Kass" <skass@drew.edu > wrote in message
> news:dGx4b.1367 4$Om1.5022@news read2.news.atl. earthlink.net.. .
>[color=green]
>>John,
>>
>> I hate to be a pest, but I believe you need the
>>date restriction in two places. The query here will
>>fail if the lowest price for a product comes from a
>>distributor that has already announced a price to become
>>effective in the future. If that is true, the future
>>price will come up on the right side of the join, since
>>there is no date restriction there. That makes the value
>>of P2.EffectiveDat e not null and in the future, and the
>>P1.Price in that row, despite being the lowest for the
>>product, is filtered out.
>>
>> Ok, I lied - I don't hate being a pest, but I do
>>think your query doesn't quite work.
>>
>>Steve[/color]
>
>
> Steve, I don't hate you for being a pest. Ok, I lied - I do hate you
> for being a pest but, of course, you happen to also be correct (again!)
> so, to a small extent, it assuages your pestiferousness . But seriously,
> in my haste, I seemed to have dropped a condition that I had originally
> specified in the outer join, that is,
> P2.EffectiveDat e <= CURRENT_TIMESTA MP
> Putting this back in leaves us with
>
> SELECT ProductName, MIN(Price) AS Price
> FROM (SELECT P1.Distributor,
> SUBSTRING(P1.Pr oductName, 1,
> CHARINDEX('(', P1.ProductName) - 2) AS
> ProductName,
> P1.EffectiveDat e AS LatestDate,
> P1.price
> FROM ProductList AS P1
> LEFT OUTER JOIN
> ProductList AS P2
> ON P1.Distributor = P2.Distributor AND
> P1.ProductName = P2.ProductName AND
> P2.EffectiveDat e > P1.EffectiveDat e AND
> P2.EffectiveDat e <= CURRENT_TIMESTA MP
> WHERE P2.EffectiveDat e IS NULL AND
> P1.EffectiveDat e <= CURRENT_TIMESTA MP)
> AS LatestPrices
> GROUP BY ProductName
>
> And Steve, thanks for the sharp eye and sharper mind.[/color]

Don't mention it. Now if I could only do something about the matching
tongue.

Steve
[color=blue]
>
> Regards,
> jag
>
>[color=green]
>>John Gilson wrote:
>>[color=darkred]
>>>"Steve Kass" <skass@drew.edu > wrote in message
>>>news:u5f4b.9 688$Om1.4472@ne wsread2.news.at l.earthlink.net ...
>>>
>>>
>>>>When I ran John's query on your sample data, It
>>>>returned the price of $25.04 for Product One, a price
>>>>that was not effective on the day I ran the query.
>>>>
>>>>Make sure your sample data has some examples where
>>>>the lowest price is a future price that has been
>>>>recorded but is not yet effective.
>>>
>>>
>>>Steve, you're absolutely right and stems from the (mis)placement
>>>of the selection criteria for the outer join. The constraint
>>>P1.Effective Date <= CURRENT_TIMESTA MP
>>>should be applied *after* the outer join condition, that is, in the
>>>WHERE clause. So this should do the right thing:
>>>
>>>SELECT ProductName, MIN(Price)
>>>FROM (SELECT P1.Distributor,
>>> SUBSTRING(P1.Pr oductName, 1,
>>> CHARINDEX('(', P1.ProductName) - 2) AS
>>> ProductName,
>>> P1.EffectiveDat e AS LatestDate,
>>> P1.price
>>> FROM ProductList AS P1
>>> LEFT OUTER JOIN
>>> ProductList AS P2
>>> ON P1.Distributor = P2.Distributor AND
>>> P1.ProductName = P2.ProductName AND
>>> P2.EffectiveDat e > P1.EffectiveDat e
>>> WHERE P2.EffectiveDat e IS NULL AND
>>> P1.EffectiveDat e <= CURRENT_TIMESTA MP)
>>> AS LatestPrices
>>>GROUP BY ProductName
>>>
>>>Regards,
>>>jag
>>>
>>>
>>>
>>>>As far as efficiency goes, all I did was look at query
>>>>plans. What I found was that John's query and mine
>>>>had virtually identical plans.
>>>>
>>>>What I did was this:
>>>>
>>>> Removed the part of product name in parentheses. If that data
>>>>is important, it should be a separate column. I removed it,
>>>>since to make this efficient there needed (I think) to be an
>>>>index with the ProductName value you want in the output, without
>>>>the extra comment, as the first column.
>>>>
>>>> Removed all cases where the same (ProductName, Distributor,
>>>>EffectiveDa te) appeared in more than one row (these probably
>>>>appeared when I removed the extra part of the product name).
>>>>
>>>> Declared (ProductName, Distributor, EffectiveDate) to be the
>>>>primary key. Maybe I missed something and this does not work
>>>>as a key, but it seemed like a good choice for an index to
>>>>make the query fast. If it's not a key, add price as
>>>>a fourth column.
>>>>
>>>> I realized now that there was extra nesting in my query.
>>>>I don't think it should have slowed it down tenfold, but the
>>>>outer two selects can be combined (if the data has no duplicates
>>>>in my key columns).
>>>>
>>>>
>>>>-- Select the lowest price
>>>>SELECT ProductName, MIN(Price)
>>>>
>>>>-- from the table
>>>
>>>>FROM ProductList P1
>>>
>>>>-- that is not a future price
>>>>WHERE P1.EffectiveDat e <= CURRENT_TIMESTA MP
>>>>
>>>>-- and that has not been superseded
>>>>AND NOT EXISTS (
>>>> -- by another price
>>>> SELECT * FROM ProductList P2
>>>> -- from the same distributor
>>>> WHERE P2.Distributor = P1.Distributor
>>>> -- for the same product
>>>> AND P2.ProductName = P1.ProductName
>>>> -- which other price has gone into effect
>>>> AND P2.EffectiveDat e <= CURRENT_TIMESTA MP
>>>> -- more recently
>>>> AND P2.EffectiveDat e > P1.EffectiveDat e
>>>>)
>>>>
>>>>-- for each product
>>>>GROUP BY ProductName
>>>>
>>>>Steve
>>>>
>>>>
>>>>netpurpos e wrote:
>>>>
>>>>
>>>>>Hi Steve,
>>>>>
>>>>>Thanks for your response. When I copied John's query, it works fine
>>>>>and gives me the correct results. I did run both your query and his
>>>>>against 330K of records, and it seems that his query runs much faster
>>>>>(more than 10 times faster). I ran your query against clean products
>>>>>names without the codes.
>>>>>
>>>>>I am too novice to even know why the big difference. Both query
>>>>>yields the same results. Can you tell why his statement is much more
>>>>>efficien t? LEFT OUTER JOIN vs EXISTS? I do want to learn from this.
>>>>>
>>>>>Also, thanks for showing me the command to import the excel file to
>>>>>db. Good to know :)
>>>>>
>>>>>Thanks,
>>>>>Netpurpo se
>>>>>
>>>>>Steve Kass <skass@drew.edu > wrote in message
>>>
>>>news:<xWV3b. 3268$Om1.1287@n ewsread2.news.a tl.earthlink.ne t>...
>>>
>>>
>>>>>>Did I miscopy John's query? It gives me the future price of $25.04
>>>>>>for Product One, but is easy to fix by adding
>>>>>>
>>>>>> AND P1.EffectiveDat e <= CURRENT_TIMESTA MP
>>>>>>
>>>>>>to the where clause of the derived table LatestPrices
>>>>>>
>>>>>>John's initial idea of NOT EXISTS still works, too, in part. (Note
>>>>>>that I blew off the ProductName parsing by taking a hatchet to that
>>>>>>column with an update...
>>>>>>
>>>>>>
>>>>>>-- Be lazy
>>>>>>UPDATE ProductList SET
>>>>>> ProductName =
>>>>>> SUBSTRING(Produ ctName, 1,CHARINDEX('(' , ProductName) - 2)
>>>>>>GO
>>>>>>
>>>>>>-- For each product, select the lowest non-future
>>>>>>-- price that has not been superseded.
>>>>>>SELECT ProductName, MIN(Price) as Price -- get the lowest price
>>>>>
>>>>>>FROM (
>>>>>
>>>>>
>>>>>> SELECT ProductName, Price -- from all non-future prices
>>>>>> FROM ProductList P1
>>>>>> WHERE P1.EffectiveDat e <= CURRENT_TIMESTA MP
>>>>>> AND NOT EXISTS ( -- that have not been superseded
>>>>>> SELECT * FROM ProductList P2
>>>>>> WHERE P2.Distributor = P1.Distributor
>>>>>> AND P2.ProductName = P1.ProductName
>>>>>> AND P2.EffectiveDat e <= CURRENT_TIMESTA MP
>>>>>> AND P2.EffectiveDat e > P1.EffectiveDat e
>>>>>> )
>>>>>>) T
>>>>>>GROUP BY ProductName -- for each product
>>>>>>go
>>>>>>
>>>>>>By the way, the delimited data was no trouble. I pasted it into
>>>>>>Excel, did Text To Columns, named the data region, and inserted it with:
>>>>>>
>>>>>>insert into [ProductList]
>>>>>>select Manufacturer, ProductName, Price, EffectiveDate
>>>>>
>>>>>>from OpenRowset(
>>>>>
>>>>>
>>>>>> 'Microsoft.Jet. OLEDB.4.0',
>>>>>> 'Excel 8.0;Database=e: \excel\ProductL ist.xls',
>>>>>> 'select * from ProductList')
>>>>>>
>>>>>>Be sure to close the Excel file before inserting.
>>>>>>
>>>>>>-- Steve Kass
>>>>>>-- Drew University
>>>>>>-- Ref: 2498EA13-1756-4C81-9307-25AFD5BB451D
>>>>>>
>>>>>>
>>>>>>
>>>>>>netpurpos e wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>>Hi Jag,
>>>>>>>
>>>>>>>Thanks a lot!! It works like a charm! Your query saves me a lot of headache.
>>>>>>>
>>>>>>>I have struggled with this for quite a while now and I am glad I find help here.
>>>>>>>
>>>>>>>Again, thank you very much! I really appreciate your help in such a short time!
>>>>>>>
>>>>>>>Regard s,
>>>>>>>Netpurpo se
>>>>>>>
>>>>>>>
>>>>>>>"John Gilson" <jag@acm.org> wrote in message
>>>
>>>news:<amO3b. 52163$ev.121550 54@twister.nyc. rr.com>...
>>>
>>>
>>>>>>>>"netpur pose" <netpurpose@hot mail.com> wrote in message
>>>>>>>>news:31 c57b38.03082910 24.6bd2a29c@pos ting.google.com ...
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>>Hi Jag,
>>>>>>>>>
>>>>>>>>>Than k you for your response. I tried the query, but it gives me a
>>>>>>>>>differ ent pricing result:
>>>>>>>>>
>>>>>>>>>Produc tName Price
>>>>>>>>>---------------------------------------- ---------------------
>>>>>>>>>Produc t One (MXT234) 28.1500
>>>>>>>>>Produc t Two (DGT6789) 44.3500
>>>>>>>>>Produc t Three (QAT556) 40.1500
>>>>>>>>>
>>>>>>>>>The correct result should be:
>>>>>>>>>
>>>>>>>>>Produc tName Price
>>>>>>>>>---------------------------------------- ---------------------
>>>>>>>>>Produc t One 33.5000
>>>>>>>>>Produc t Two 44.7500
>>>>>>>>>Produc t Three 40.4500
>>>>>>>>>
>>>>>>>>>The reason is because for Product One, Manufacturer "BBB" has a price
>>>>>>>>>of 28.15 on 2003-07-30, this price is no longer valid because "BBB"
>>>>>>>>>has more recent price of 33.5 starting on 2003-08-27. Same case with
>>>>>>>>>Produc t Two and Three (manufacturer "JJJ" overrides the 40.15 on
>>>>>>>>>2003-08-01 with 40.45 on 2003-08-04).
>>>>>>>>>
>>>>>>>>>I have to take the most recent prices from each manufacturer for a
>>>>>>>>>partic ular product (price at the latest date as of today), and then
>>>>>>>>>take the minimum price from the result.
>>>>>>>>>
>>>>>>>>>Agai n, thank you for your help. Sorry I might not explain it well in
>>>>>>>>>the beginning. Any further help is appreciated. Thank you very much
>>>>>>>>>in advance!
>>>>>>>>>
>>>>>>>>>Regard s,
>>>>>>>>>Netpur pose
>>>>>>>>
>>>>>>>>I was a little too quick on the draw and misread your requirements.
>>>>>>>>
>>>>>>>>SELEC T ProductName, MIN(Price)
>>>>>>>
>>>>>>>>FROM (SELECT P1.Distributor,
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> SUBSTRING(P1.Pr oductName, 1,
>>>>>>>> CHARINDEX('(', P1.ProductName) - 2) AS
>>>>>>>> ProductName,
>>>>>>>> P1.EffectiveDat e AS LatestDate,
>>>>>>>> P1.price
>>>>>>>> FROM ProductList AS P1
>>>>>>>> LEFT OUTER JOIN
>>>>>>>> ProductList AS P2
>>>>>>>> ON P1.Distributor = P2.Distributor AND
>>>>>>>> P1.ProductName = P2.ProductName AND
>>>>>>>> P1.EffectiveDat e <= CURRENT_TIMESTA MP AND
>>>>>>>> P2.EffectiveDat e <= CURRENT_TIMESTA MP AND
>>>>>>>> P2.EffectiveDat e > P1.EffectiveDat e
>>>>>>>> WHERE P2.EffectiveDat e IS NULL) AS LatestPrices
>>>>>>>>GROUP BY ProductName
>>>>>>>>
>>>>>>>>Regards ,
>>>>>>>>jag
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>>"Joh n Gilson" <jag@acm.org> wrote in message
>>>
>>>news:<_uI3b. 51441$ev.119354 02@twister.nyc. rr.com>...
>>>
>>>
>>>>>>>>>>"netp urpose" <netpurpose@hot mail.com> wrote in message
>>>>>>>>>>news: 31c57b38.030829 0040.6a560bd6@p osting.google.c om...
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>>I need to extract data from this table to find the lowest prices of
>>>>>>>>>>>ea ch product as of today. The product will be listed/grouped by the
>>>>>>>>>>>na me only, discarding the product code - I use SUBSTRING(Produ ctName,
>>>>>>>>>>>1, CHARINDEX('(', ProductName)-2).
>>>>>>>>>>>
>>>>>>>>>>>I can get this result, but I had to use several views (totally
>>>>>>>>>>>inef ficient). I think this can be done in one efficient/fast query,
>>>>>>>>>>>bu t I can't think of one.
>>>>>>>>>>>
>>>>>>>>>>>In the case that one query is not possible, is there other efficient
>>>>>>>>>>>wa y to get the results? There are about 300K records in the table.
>>>>>>>>>>>
>>>>>>>>>>>An y help is appreciated! Thanks a lot in advance!
>>>>>>>>>>>
>>>>>>>>>>>Than ks,
>>>>>>>>>>>Netp urpose
>>>>>>>>>>
>>>>>>>>>>SELEC T P1.ProductName, P1.Price
>>>>>>>>>
>>>>>>>>>>FRO M ProductList AS P1
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>>WHE RE EffectiveDate <= CURRENT_TIMESTA MP AND
>>>>>>>>>> NOT EXISTS
>>>>>>>>>> (SELECT *
>>>>>>>>>> FROM ProductList AS P2
>>>>>>>>>> WHERE SUBSTRING(P1.Pr oductName, 1,
>>>>>>>>>> CHARINDEX('(', P1.ProductName) - 2) =
>>>>>>>>>> SUBSTRING(P2.Pr oductName, 1,
>>>>>>>>>> CHARINDEX('(', P2.ProductName) - 2)
>>>
>>>AND
>>>
>>>
>>>>>>>>>> P2.EffectiveDat e <= CURRENT_TIMESTA MP AND
>>>>>>>>>> P2.Price < P1.Price)
>>>>>>>>>>
>>>>>>>>>>Regar ds,
>>>>>>>>>>jag
>>>>>>>>>>
>>>>>>>>>>
>>>>
>>>[/color][/color]
>
>[/color]

Need help with query

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