ORACLE SYS_REFCURSOR VS REF CURSOR

CURSOR是强类型，SYS_REFCURSOR 是弱类型（类似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;
/

--类型报错
declare
  cur pkg.tcur;
begin
  open cur for 
    select "a" s, 1 n from dual; --跟游标定义的类型不一致
end;
/

--正常运行
declare
  cur pkg.tcur;
begin
  open cur for 
    select "kkk" n from dual;
end;
/

--正常运行
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; --跟上面的游标类型不一致

close cur;
end;
/