求帮忙解决PLSQL块代码的问题,不胜感激

declare o_order_number varchar2(50);
  mark_create_id number(10);
  cursor acnt_first_cur is
  select
  t1.order_number,t1.id
  from mark_create_bak_20110630 t1, mark_create t2
  where t1.id=t2.id and t1.sp_id<>t2.sp_id
and t1. addition_number is not null and t1.is_used=0;
  begin
  open acnt_first_cur;
  loop
  exit when acnt_first_cur%notfound;
  fetch acnt_first_cur bulk collect into o_order_number, mark_create_id
  forall i in 1 .. mark_create_id.count
  update mark_create
  set order_number = o_order_number(i)
  where id = mark_create_id(i);
  commit;
  end loop;
  end;

上面的语句在PLSQL中老是报错,报错如下:

ORA-06550: 第 3 行, 第 2 列:
PLS-00103: 出现符号 ""在需要下列之一时:
begin function pragma
procedure subtype type
current cursor delete
exists prior
求PLSQL高手解释,小弟万分感激谢谢

[code="sql"]
--需要加引号吧?
t1.is_used='0'[/code]