ORACLE SYS_REFCURSOR VS REF CURSOR

CURSOR是強類型，SYS_REFCURSOR 是弱類型（類似C#的var）。

Cursor：

create or replace package pkg as
  cursor cur is
    select 1 n from dual;    
  type tcur is ref cursor return pkg.cur%rowtype;  
end pkg;
/

--類型報錯
declare
  cur pkg.tcur;
begin
  open cur for 
    select 'a' s, 1 n from dual; --跟游標定義的類型不一致
end;
/

--正常運行
declare
  cur pkg.tcur;
begin
  open cur for 
    select 'kkk' n from dual;
end;
/

--正常運行
declare
  cur pkg.tcur;
begin
  open cur for 
    select 900 n from dual;
end;
/

Sys_refcursor:

declare
cur sys_refcursor;
begin
open cur for 
select 'a' s, 1 n from dual;

close cur;

open cur for 
select 9 n from dual; --跟上面的游標類型不一致

close cur;
end;
/