<suvisor.root@gmail.com> wrote:
> select * from testt where id = (random()* 100000)::integer;
>
> And sometimes it comes out something like this:
> id | val
> -------+--------
> 11894 | 15051
> 29233 | 42198
> 80725 | 90213
> 85688 | 100992
> 88017 | 108075
> (5 rows)
> Here can be 2, 3 or other rows amount in result... But must be
> only one!
No, what you have written will scan the entire table and give each
row a 1 in 100000 chance of being selected. Maybe something like
this would give you what you want:
select t.* from (select (random()* 100000)::integer) n(r)
join testt t on (t.id = n.r);
By the way, you might want to tweak that random number before
casting it to int, or you might not get *any* rows back:
test=# select ('0.0000000001'::float * 100000)::int;
int4
------
0
(1 row)
Maybe something like:
(select floor(random() * 100000)::int + 1)
-Kevin