Re: Search a range of cases/records

am Thu, dem 01.02.2007, um 12:56:28 -0800 mailte Wei ZOU folgendes:
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> 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.price between 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 | 5
100 | 5 | 6
101 | 2 | 6
102 | 0 | 2
103 | 0 | 0
104 | 0 | 1
105 | 1 | 1
(11 rows)

Andreas
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Andreas Kretschmer
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