Are you sur you don't want a moving windows
(stddev on 0 to 50 , then stdev on 1 to 51)
..
If you don't want moving windows your query would look like
DROP TABLE IF EXISTS your_data;
CREATE TABLE your_data AS
SELECT s as gid , random() as your_data_value
FROM generate_series(1,1) as s ;
SEL
Hi Pierre,
How do you know in which group each row belongs? If you don't care how
the rows are grouped, you can say this:
create table foo (v float);
insert into foo select random() from generate_series(1, 100) s(a);
select n % 50 g, stddev(v) from (select row_number() over () n, v from
foo)
Pierre Hsieh wrote
> Hi
>
> This table just has a column which type is integer. There are one million
> data in this table. I wanna calculate standard deviation on each 50 data
> by
> order. It means SD1 is from data 1 to data 50, SD2 is from data 51 to
> 100 Is there anyone who can give me so
Hi
This table just has a column which type is integer. There are one million
data in this table. I wanna calculate standard deviation on each 50 data by
order. It means SD1 is from data 1 to data 50, SD2 is from data 51 to
100 Is there anyone who can give me some suggestions? Thanks
Pierre
