Random number or string generator package

create or replace package random

is

   procedure srand(new_seed in number);

   procedure get_rand(r OUT number);

   procedure get_rand_max(r OUT number, n IN number);

   function  rand return number;

   function  rand_max(n IN number) return number;

   function  rand_string(ssiz IN number) return varchar2;

   function  smaller(x IN number, y IN number) return number;

   pragma restrict_references(rand, WNDS);

   pragma restrict_references(rand_max, WNDS);

   pragma restrict_references(random, WNDS, RNPS);

   pragma restrict_references(rand_string, WNDS);

   pragma restrict_references(smaller, WNDS);

end random;

/

create or replace package body random

is

   multiplier   constant number := 22695477;

   increment    constant number := 1;

   "2^32"       constant number := 2 ** 32;

   "2^16"       constant number := 2 ** 16;

   "0x7fff"     constant number := 32767;

   Seed         number          := 1;

   function  smaller(x IN number, y IN number) return number is

   begin

        if x <= y then

            return x;

        else

            return y;

        end if;

   end smaller;

   function rand_string(ssiz IN number) return varchar2 is

     i      number;

     m      number;

     c      char;

     result varchar2(2000) := '';

   begin

        m := smaller(ssiz,2000);

        for i in 1..m loop

            c := substr('abcdefghijklmnopqrstuvwxyz0123456789',rand_max(36),1);

            result := result || c;

        end loop;

        return result;

   end rand_string;

   procedure srand(new_seed in number) is

   begin

     Seed := new_seed;

   end srand;

   function rand return number is

   begin

     Seed := mod(multiplier * Seed + increment, "2^32");

     return bitand(Seed/"2^16", "0x7fff");

   end rand;

   procedure get_rand(r OUT number) is

   begin

     r := rand;

   end get_rand;

   function rand_max(n IN number) return number is

   begin

     return mod(rand, n) + 1;

   end rand_max;

   procedure get_rand_max(r OUT number, n IN number) is

   begin

     r := rand_max(n);

   end get_rand_max;

begin

   select userenv('SESSIONID')

   into   Seed

   from   dual;

end random;

/

-- Some examples:

select random.rand_max(10) from dual;

select random.rand_max(10) from dual;

select random.rand_string(20) from dual;

select random.rand_string(20) from dual;