SQLはこれに最適な言語ではないことはわかっていますが、これは引数Nを取り、100万から1000万の間の素数（N = 10,000,000）を見つける関数を書くための宿題です。私はPostgresqlを使用しています。これが私の試みです：
--First create table Numbers with all numbers from 1 to 10000000 in it
create table numbers(number bigint);
--Use this function to fill it in:
create or replace function populate(top bigint) RETURNS void as $$
declare
i bigint:=1;
begin
while(i<=top) LOOP
insert into numbers(number)
values(i);
i:=i+1;
END LOOP;
END; $$ LANGUAGE plpgsql;
--Function primes that returns all primes up to N
create or replace function primes(N bigint) RETURNS void AS $$
DECLARE
first bigint :=3;
last bigint :=2;
BEGIN
--create table t1 and insert all odd integers from 3 to N (and 2)
create table t1(a bigint);
INSERT into t1(a)
select number
from numbers
where (number%2 <> 0 or number = 2)
AND number<=N AND number<>1;
--Use Sieve of Erastothenes to find primes
while (last < sqrt(n)) LOOP
first:= (select * from t1 where a>last order by a limit 1);
last:= first* first;
--delete from list of primes all multiples of the primes in the range of first-last
-- (first run-through is primes in range of 3-9, second run-through would be primes in range of 11-121, etc.)
delete from t1
where a in (select n1.number * t.a
from t1 as t
inner join numbers as n1
on n1.number >= t.a
and n1.number<= n/t.a
where t.a>=first
and t.a<last);
END LOOP;
END; $$ LANGUAGE plpgsql;