am Thu, dem 01.02.2007, um 12:56:28 -0800 mailte Wei ZOU folgendes:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Greetings:
>
> I have a dataset of two columns:
> price amount
> 99.5 10000
> 99.7 8000
> 100 3000
> 100.1 1000
> 100.5 500
> 100.8 1500
> 105 2000
> 200 100
> etc
> I have to write a SQL query on how many price tags are within [price+-1]
> such as 98.5 to 100.5, 100+-1,etc for each records.
> Here I know the price tags counts are 5 for 99.5-100.5, 5 for
> 99.7-100.7, 6 for 99-101, etc
> How should I do for all of the records?
Perhaps something like below:
test=*# select s, sum(case when price.price between s-0.5 and s+0.5 then 1 else 0 end) as "+-1", sum(case when
price.pricebetween s-1.5 and s+1.5 then 1 else 0 end) as "+-2"
from price,
generate_series(95, 105) as s
group by s
order by s; s | +-1 | +-2
-----+-----+----- 95 | 0 | 0 96 | 0 | 0 97 | 0 | 0 98 | 0 | 1 99 | 1 | 5100 | 5 | 6101 | 2 |
6102 | 0 | 2103 | 0 | 0104 | 0 | 1105 | 1 | 1
(11 rows)
Andreas
--
Andreas Kretschmer
Kontakt: Heynitz: 035242/47150, D1: 0160/7141639 (mehr: -> Header)
GnuPG-ID: 0x3FFF606C, privat 0x7F4584DA http://wwwkeys.de.pgp.net
