Re: short-cutting if sum()>constant

Hello

I found one ugly trick. You can multiply lines and SUM > cons could be
replaced limit clause:

postgres=# select * from data;a
---321423
(6 rows)

Then SELECT * FROM WHERE and stop when SUM(a) = n

then

postgres=# select generate_series(1,a) from data;generate_series
-----------------              1              2              3              1              2              1
1              2              3              4              1              2              1              2
3

So If I would to check if there are sum(a) >= 10 then I can use LIMIT
10. If query returns ten rows, then result is true, else result is
false

select a, (a = generate_series(1,a))::int from data limit 12; -- stop
after sum(a) = 12

postgres=# select sum(x) from (select 1 as x,(a =
generate_series(1,a))::int from data limit 12) s;sum
----- 12 --              12 is eq 12, so test is successful

(1 row)


Regards
Pavel Stehule

2009/12/22 Ivan Sergio Borgonovo <mail@webthatworks.it>:
> Hi,
>
> I'd like to know if
>
> select sum(qty) from t where status=37;
>
> is > constant.
>
> qty is always >0.
>
> Is there a way to skip examining further rows and return a result
> ASAP?
>
>
> --
> Ivan Sergio Borgonovo
> http://www.webthatworks.it
>
>
> --
> Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-sql
>