Generate dummy data in Oracle table (Courtesy asktom.oracle.com)

create or replace procedure do_dummy_data( p_tname in varchar2,
p_records in number )
 authid current_user
 as
     l_insert long;
     l_rows   number default 0;
 begin

    execute immediate 'create table clone_' || p_tname ||
                      ' as select * from ' || p_tname ||
                      ' where 1=0';

     l_insert := 'insert into clone_' || p_tname ||
                 ' select ';

     for x in ( select data_type, data_length,
                 rpad( '9',data_precision,'9')/power(10,data_scale) maxval
                  from user_tab_columns
                 where table_name = 'CLONE_' || upper(p_tname)
                 order by column_id )
     loop
         if ( x.data_type in ('NUMBER', 'FLOAT' ))
         then
             l_insert := l_insert || 'dbms_random.value(1,' || x.maxval || '),';
         elsif ( x.data_type = 'DATE' )
         then
             l_insert := l_insert ||
                   'sysdate+dbms_random.value+dbms_random.value(1,1000),';
         else
             l_insert := l_insert || 'dbms_random.string(''A'',' ||x.data_length || '),';
         end if;
     end loop;
     l_insert := rtrim(l_insert,',') ||
                   ' from all_objects where rownum <= :n';

     loop
         execute immediate l_insert using p_records - l_rows;
         l_rows := l_rows + sql%rowcount;
         exit when ( l_rows >= p_records );
     end loop;
 end;
 /