MySQL

with recursive sequence as (
    select 2 as num from dual
    union all
    select num + 1 num
    from sequence 
    where num < 1000
),
primeNumbers as (
    select num 
    from sequence s1
    where not exists (
        select 1 
        from sequence s2 
        where (s2.num > 1 and s2.num < s1.num) and 
            (s1.num % s2.num = 0)
    )
)
select GROUP_CONCAT(num SEPARATOR '&') 
from primeNumbers;

WITH RECURSIVE numbers AS ( SELECT 2 AS n UNION ALL SELECT n + 1 FROM numbers WHERE n < 1000 ) SELECT GROUP_CONCAT(n SEPARATOR '&') FROM numbers AS n1 where NOT EXISTS( SELECT 1 FROM numbers AS n2 WHERE n2.n < n1.n AND n1.n % n2.n =0)

-- suma +1 hasta llegar a 999

WITH RECURSIVE numbers(n) AS ( SELECT 2 UNION ALL SELECT n + 1 FROM numbers WHERE n < 1000 ),

-- valida si es mayor a 1, si su residuo es 0 y solo tomara los números que esten hasta la raíz del número que se esta comprobando (así limita la cantidad de número para validar la condición)

primes AS ( SELECT n FROM numbers n1 WHERE NOT EXISTS ( SELECT 1 FROM numbers n2 WHERE n2.n <= SQRT(n1.n) AND n1.n % n2.n = 0 AND n2.n > 1 ) )

SELECT GROUP_CONCAT(n SEPARATOR '&') FROM primes;

with e1(n) as (select 1 union all select 1 union all select 1 union all select 1 union all select 1 union all select 1 union all select 1 union all select 1 union all select 1 union all select 1)

, e2(n) as (select 1 from e1 a, e1 b)

, e3(n) as (select 1 from e2 a, e2 b)

, tt(n) as (select top 1000 row_number() over (order by (select null))from e3)

SELECT STRING_AGG(CAST(t.n AS varchar(10)), '&') WITHIN GROUP (ORDER BY t.n) FROM tt t WHERE t.n > 1 AND NOT EXISTS ( SELECT 1 FROM tt d WHERE d.n > 1 AND d.n < t.n AND t.n % d.n = 0 );

WITH CTE AS ( SELECT 2 AS Num UNION ALL SELECT NUM + 1 AS NUM FROM CTE WHERE NUM < 1000 ) SELECT STRING_AGG(CAST(N1.NUM AS VARCHAR(10)),'&') FROM CTE AS N1 WHERE NOT EXISTS ( SELECT 1 AS NUM FROM CTE AS N2 WHERE N1.NUM > 1 AND N1.NUM > N2.NUM AND N1.NUM%N2.NUM = 0

) OPTION(MAXRECURSION 1000) go