About runtime sequence creation and view dare pre commmit.

Question

Dear All,
My 2 New Question are:
1)Could Oracle suggest to create sequence(DDL) from run-time.That means I need(My client requirement) regenerate of sequence(I know it is possible by cycle but i don't know MAX value when it will cycle)as monthly or a specific time so I want to drop sequence and create sequence by a)Programmetically runtime
b) Oracle scheduler runtime .
Have any good and better Idea? Any risk factor?
Note that at a time possibly more than 100 users will data entry with our software.
2)My New query is Could I view table data which was not yet COMMITTED from other session-other user.
Regards and Thanking you,
ZAKIR
Analyst ,
SynesisIT,
www.Synesisit.com
=====

Answer 1

I tried that, but there are too many trouble.
For only references.
-- Usage
Procedures
　execute periodic_seq.seq_def   create sequence
　execute periodic_seq.seq_undef drop sequence
Functions
　　periodic_seq.nextvalue
　　　get nextval of specified sequence
　　periodic_seq.currvalue
　　　get currval of specified sequence
seq_def
　in_seq_name varchar2 (30)
    sequence name (current schema)
　in_trunc_unit varchar2
　　'yyyy','mm','dd','hh24','mi' : format on trunc(date)
seq_def
　in_owner varchar2 (30)
　　schema name
　in_seq_name varchar2 (30)
　　sequence name
　in_trunc_unit varchar2
　　'yyyy','mm','dd','hh24','mi' : format on trunc(date)
　incr_by integer (default:1)
　　increment by
　start_with integer (default:1)
　　start with
　maxvalue integer (default:to_number('1e27'))
　　maxvalue
　minvalue integer (default:1)
　　minvalue
　cycle varchar2 (default:'N')
　　'Y':cycle/'N':nocycle
　cache integer (default:20)
　　cache
　time_order varchar2 (default:'N')
　　'Y':order/'N':noorder
seq_undef
　in_seq_name varchar2 (30)
    sequence name (current schema)
seq_undef
　in_owner varchar2 (30)
　　schema name
　in_seq_name varchar2 (30)
　　sequence name
nextvalue
　in_seq_name varchar2 (30)
    sequence name (current schema)
nextvalue
  in_owner varchar2 (30)
　　schema name
　in_seq_name varchar2 (30)
　　sequence name
currvalue
　in_seq_name varchar2 (30)
    sequence name (current schema)
currvalue
  in_owner varchar2 (30)
　　schema name
　in_seq_name varchar2 (30)
　　sequence name
-- Source --
-- Control table
create table cycle_seq_ctrl
(sequence_name varchar2(30) not null
,min_value integer
,max_value integer
,increment_by integer not null
,cycle_term varchar(10) default('dd') not null
,last_number integer not null
,reset_time date
,prev_nextval integer not null
,constraint pkey_cycle_seq_ctrl primary key (sequence_name)
organization index
create or replace
package cycle_seq
authid current_user
is
function nextvalue
(seq_name varchar2
,in_date date := sysdate
) return integer
function currvalue
(seq_name varchar2
) return integer
procedure seq_def
(seq_name varchar2
,cycleterm varchar2 := 'DD' /* Defaults : reset by a day */
,incr_by integer := 1
,start_with integer := 1
,maxvalue integer := to_number('1e27')
,minvalue integer := 1
procedure seq_undef
(seq_name varchar2
end; -- package cycle_seq
create or replace
package body cycle_seq
is
  type currval_tab_type is table of integer index by varchar2(30);
  currval_tab currval_tab_type;
function nextvalue
(seq_name varchar2
,in_date date := sysdate
) return integer
is
pragma autonomous_transaction;
  timeout_on_nowait exception;
  timeout_on_wait_sec exception;
  pragma exception_init(timeout_on_nowait, -54);
  pragma exception_init(timeout_on_wait_sec, -30006);
  p_seqname cycle_seq_ctrl.sequence_name%type;
  p_ctrl cycle_seq_ctrl%rowtype;
  p_currtime date;
  p_nextval integer;
begin
  p_currtime := in_date;
  p_seqname := upper(trim(seq_name));
  select *
    into p_ctrl
    from cycle_seq_ctrl
   where sequence_name = p_seqname
  for update wait 1
  if (p_ctrl.cycle_term<>'SS') then
    p_currtime := trunc(p_currtime,p_ctrl.cycle_term);
  end if;
  -- need to reset
  if (p_ctrl.reset_time < p_currtime) then
    if (p_ctrl.increment_by > 0) then
      p_nextval := p_ctrl.min_value;
    elsif (p_ctrl.increment_by < 0) then
      p_nextval := p_ctrl.max_value;
    else
      p_nextval := p_ctrl.last_number;
    end if;
    update cycle_seq_ctrl
      set last_number = p_nextval
         ,reset_time = p_currtime
         ,prev_nextval = last_number + increment_by
    where sequence_name = p_seqname
    currval_tab(p_seqname) := p_nextval;
    commit;
    return p_nextval;
  end if;
  -- already reseted (in a same second)
  if (p_ctrl.reset_time = p_currtime) then
    p_nextval := p_ctrl.last_number + p_ctrl.increment_by;
    update cycle_seq_ctrl
      set last_number = p_nextval
    where sequence_name = p_seqname
    currval_tab(p_seqname) := p_nextval;
    commit;
    return p_nextval;
  -- already reseted
  else
    p_nextval := p_ctrl.prev_nextval + p_ctrl.increment_by;
    update cycle_seq_ctrl
      set prev_nextval = p_nextval
    where sequence_name = p_seqname
    currval_tab(p_seqname) := p_nextval;
    commit;
    return p_nextval;
  end if;
exception
  when no_data_found then
    raise_application_error(-20800,
       'cycle_seq.seq_def('''||seq_name
       ||''') has not been called.');
  when timeout_on_nowait or timeout_on_wait_sec then
    raise_application_error(-20899,
       'cycle_seq.nextvalue('''||seq_name
       ||''') is time out.');
  when others then
    raise;
end
function currvalue
(seq_name varchar2
) return integer
is
  p_seqname cycle_seq_ctrl.sequence_name%type;
begin
  p_seqname := upper(trim(seq_name));
  return currval_tab(upper(seq_name));
exception
  when no_data_found then
    raise_application_error(-20802,
       'cycle_seq.nextvalue('''
       ||seq_name||''') has not been called in this session.');
  when others then
    raise;
end
procedure seq_def
(seq_name varchar2
,cycleterm varchar2 := 'DD'
,incr_by integer := 1
,start_with integer := 1
,maxvalue integer := to_number('1e27')
,minvalue integer := 1
is
  p_seqname cycle_seq_ctrl.sequence_name%type;
  p_currtime date;
  p_cycleterm cycle_seq_ctrl.cycle_term%type;
begin
  p_currtime := sysdate;
  p_seqname := upper(trim(seq_name));
  p_cycleterm := upper(trim(cycleterm));
  if (p_cycleterm<>'SS') then
    p_currtime := trunc(p_currtime,cycleterm);
  end if;
  insert into cycle_seq_ctrl
    (sequence_name
    ,min_value
    ,max_value
    ,increment_by
    ,cycle_term
    ,last_number
    ,reset_time
    ,prev_nextval
  values
    (p_seqname
    ,minvalue
    ,maxvalue
    ,incr_by
    ,p_cycleterm
    ,start_with - incr_by
    ,p_currtime
    ,start_with - incr_by
  commit; -- Because this is as like a DDL
exception
  when dup_val_on_index then
    raise_application_error(-20955,
       'already defined with '
      ||'cycle_seq.seq_def('''||seq_name||''')');
  when others then
    raise;
end
procedure seq_undef
(seq_name varchar2
is
  p_seqname cycle_seq_ctrl.sequence_name%type;
begin
  p_seqname := upper(trim(seq_name));
  delete from cycle_seq_ctrl
  where sequence_name = p_seqname
  commit; -- Because this is as like a DDL
end
end; -- package body cycle_seq
/