使用Oracle“with”与使用表的行为不同

尝试了以下代码:

--------------- Setup ------------
drop table suk_rc_t1;

create table suk_rc_t1 (x number, y number);

insert into suk_rc_t1(x) values(1); 

commit;

create or replace function suk_instn_id_wrap(
call_id pls_integer )
 return pls_integer as
begin
  dbms_output.put_line('suk_instn_id_wrap ' || call_id);
  --return suk_instn_id;
  return 123;
end;
/ 

--------------- How many RUNs of suk_instn_id_wrap in 2 queries below ? ------------

select 3 from suk_rc_t1
where (coalesce (y, suk_instn_id_wrap(1)) = suk_instn_id_wrap(2)
       or suk_instn_id_wrap(3) is null);    

begin
   dbms_output.put_line('Done');
end;
/
with suk_rc_t1 as (select 1 x, null y from dual)
select 3 from suk_rc_t1
where (coalesce (y, suk_instn_id_wrap(1)) = suk_instn_id_wrap(2)
       or suk_instn_id_wrap(3) is null);    
begin
   dbms_output.put_line('Done');
end;
/

我希望得到同样的结果。相反,我得到了:

suk_instn_id_wrap 3
suk_instn_id_wrap 1
suk_instn_id_wrap 2
Done

suk_instn_id_wrap 1
suk_instn_id_wrap 2
Done

有人能解释这种行为吗?