ORACLE随机数DBMS_RANDOM包

 declare 
  i number:=;  
  j number:=;  
 begin 
  for k in .. loop  
  i:= dbms_random.normal;  
   if i > j  
    then j:=i;  
   end if;  
  end loop;  
  dbms_output.put_line(j);  
 end; 

  SQL > column value format 9.99999999999999999999999999999999999999
  SQL > select dbms_random.value from dual;

                    VALUE
  -----------------------------------------
   .58983014999643548701631750396301271752

  SQL > column value format 999.999999999999999999999999999999999999
  SQL > select dbms_random.value(100,500) value from dual;
                    VALUE
  -----------------------------------------
   412.150194612502916808701157054098274240

  'u','U' : upper case alpha characters only
  'l','L' : lower case alpha characters only
  'a','A' : alpha characters only (mixed case)
  'x','X' : any alpha-numeric characters (upper)
  'p','P' : any printable characters

  SQL > column value format a30
  SQL > select dbms_random.string('u',30) value from dual;
  VALUE
  ------------------------------
  VTQNLGISELPXEDBXKUZLXKBAJMUTIA

  SQL > select dbms_random.string('l',30) value from dual;
  VALUE
  ------------------------------
  uqygsbquingfqdytpgjvdoblxeglgu

  SQL > select dbms_random.string('a',30) value from dual;
  VALUE
  ------------------------------
  NGTGkQypuSWhBfcrHiOlQwOUXkqJjy

  SQL > select dbms_random.string('x',30) value from dual;
  VALUE
  ------------------------------
  UVWONYJMXT31VEFPD736WJCJ5QT6BD

  SQL > select dbms_random.string('p',30) value from dual;
  VALUE
  ------------------------------
  :mak$(WT4M_7c/+f[_XUscf$P Zcq{

  -- Seed with a binary integer
  PROCEDURE seed(val IN BINARY_INTEGER );
  PRAGMA restrict_references (seed, WNDS );

  -- Seed with a string (up to length 2000)
  PROCEDURE seed(val IN VARCHAR2 );
  PRAGMA restrict_references (seed, WNDS );

 -- Obsolete, just calls seed(val)
  PROCEDURE initialize(val IN BINARY_INTEGER );
  PRAGMA restrict_references (initialize, WNDS );