....
vcSeqBody:='CREATE SEQUENCE '||vcTName||'_SEQ'||chr( 13 )
          ||'minvalue 1'||chr( 13 )
          ||'maxvalue 999999999999999999999999999'||chr( 13 )
          ||'start with 1'||chr( 13 )
          ||'increment by 1'||chr( 13 )
          ||'nocache'||chr( 13 )
          ||'cycle;';
 vcSeqDropBody:='Drop SEQUENCE '||vcTName||'_SEQ;';
  ......
	Select count(*) as a into u
        	from  sys.all_sequences  o
        	where  o.sequence_name= vcTName||'_SEQ';
if U= 1  then			        
 execute immediate  vcSeqDropBody;
 commit;
end if;  
 execute immediate vcSeqBody;
 commit;

CREATE OR REPLACE TRIGGER ACCBAL1_INC
BEFORE INSERT ON ACCBAL1 FOR EACH ROW
declare
 I integer;
begin
 if :new.IDACCBAL1 is null then
  SELECT ACCBAL1_SEQ.NextVal into :new.IDACCBAL1 from Dual;
 else
  SELECT ACCBAL1_SEQ.NextVal into I from dual;
  while :new.IDACCBAL1>I loop 
    SELECT ACCBAL1_SEQ.NextVal into I from dual;
  end loop;
 end if;
end ACCBAL1_INC;

CREATE OR REPLACE TRIGGER ACCBAL1_INC
BEFORE INSERT ON ACCBAL1 FOR EACH ROW
 I integer;
begin
 if :new.IDACCBAL1 is null then
  SELECT ACCBAL1_SEQ.NextVal into :new.IDACCBAL1 from Dual;
 else
  SELECT ACCBAL1_SEQ.NextVal into I from dual;
  while :new.IDACCBAL1>I loop 
    SELECT ACCBAL1_SEQ.NextVal into I from dual;
  end loop;
 end if;
end ACCBAL1_INC

    vcTrIncBody:='CREATE OR REPLACE TRIGGER '||vcTName||'_INC'||chr( 13 )
        	||'BEFORE INSERT ON '||vcTName||' FOR EACH ROW as'||chr( 13 )
          ||'declare'||chr( 13 )          
          ||' I integer;'||chr( 13 )
          ||'begin'||chr( 13 )
  				||' if :new.'||vcPKColName||' is null then'||chr( 13 )
     			||'  SELECT '||vcTName||'_SEQ.NextVal into :new.'||vcPKColName||' from Dual;'||chr( 13 )
          ||' else'||chr( 13 )||'  SELECT '||vcTName||'_SEQ.NextVal into I from dual;'||chr( 13 )
          ||'  while :new.'||vcPKColName||'>I loop '||chr( 13 )||'    SELECT '||vcTName||'_SEQ.NextVal into I from dual;'||chr( 13 )   
          ||'  end loop;'||chr( 13 )||' end if;'||chr( 13 )||'end '||vcTName||'_INC';
 execute immediate vcTrIncBody;
commit;