Drop squence in a trigger

Question

i have made a statment trigger that drop a sequence and start a new one for each day:
SQL> create table b2 (n number(10),da date);
Table created.
SQL> create sequence seq_b2;
Sequence created.
1 create or replace trigger b2 before insert on emp
2 declare
3 i date;
4 begin
5 select max(da) from b2 into i
6 if sysdate > i then
7 drop sequence seq_b2;
8 create sequence seq_b2;
9 end if;
10* end;
SQL> /
Warning: Trigger created with compilation errors.
SQL> show error;
Errors for TRIGGER B2:
LINE/COL ERROR
4/1 PL/SQL: SQL Statement ignored
4/24 PL/SQL: ORA-00933: SQL command not properly ended
7/1 PLS-00103: Encountered the symbol "CREATE" when expecting one of
the following:
begin case declare end exception exit for goto if loop mod
null pragma raise return select update while with
<an identifier> <a double-quoted delimited-identifier>
<a bind variable> << close current delete fetch lock insert
open rollback savepoint set sql execute commit forall merge
<a single-quoted SQL string> pipe
so is there any suggestion(''Hint'' i am droping the
squence and recreate it becuause i want the squence to be unique only at the same day)

Answer 1

Mohannad,
if you REALLY want to do it
you may use nigthly started job which
will recreate you sequence.
Also one of the option would be to create cycled sequence
with large enough MAXVALUE parameter and recycle it
each night to 1:
SQL> create sequence cycled_seq start with 1
  2  increment by 1 maxvalue 10000 cycle
  3  /
&nbsp
Sequence created.
&nbsp
SQL> select cycled_seq.nextval from dual;
&nbsp
   NEXTVAL
         1
&nbsp
SQL> /
&nbsp
   NEXTVAL
         2
&nbsp
SQL> /
&nbsp
   NEXTVAL
         3
&nbsp
SQL> /* At the day end */
SQL> declare
  2   id number;
  3  begin
  4   id := 0;
  5   while(id != 10000) loop
  6     select cycled_seq.nextval into id from dual;
  7   end loop;
  8  end;
  9  /
&nbsp
PL/SQL procedure successfully completed.
&nbsp
SQL> select cycled_seq.nextval from dual;
   NEXTVAL
         1Oracle jobs description is there:
http://download-west.oracle.com/docs/cd/B10501_01/appdev.920/a96612/d_job.htm#999107
But to be quite franky
there are hardly any reasonable motives
to restart sequence number
every day and to compose this complex key.
Rgds.