PL SQL For Loop Sys_RefCursor

问题

I'm using Oracle 12c. In PL/SQL I can do this

set serveroutput on
declare
begin
  for x in (select 1 as y from dual) loop
    dbms_output.put_line(x.y);
  end loop;
end;

I can also do this...

set serveroutput on
declare
  cursor c1 is
    select 1 as y from dual;
begin
  for x in c1 loop
    dbms_output.put_line(x.y);
  end loop;
end;

So far, so good. But can I do this with a sys_refcursor? I am aware I could do it with a fetch/while loop but prefer the for loop syntax (I think it is a lot cleaner)...

set serveroutput on
declare
  cur sys_refcursor;
begin
  cur := Package.GetData(1234);
  fetch cur into y;
  while cur%FOUND loop
    dbms_output.put_line(y);
    fetch cur into y;
  end loop;
end;

I want to do...

set serveroutput on
declare
  cur sys_refcursor;
begin
  cur := PACKAGE.GetData(1234); -- This returns a sys_refcursor
  for x in cur loop
    dbms_output.put_line(x.y);
  end loop;
end;

Error report -
ORA-06550: line 5, column 16:
PLS-00221: 'cur' is not a procedure or is undefined

Is there a mechanism to for loop through the sys_refcursor (rather than the fetch into/while loop)? Perhaps something new-fangled in 12c that I don't know about...?

回答1:

SYS_REFCURSOR is merely a pre-declared weak ref cursor. There is no such mechanism to loop through sys_refcursor without fetching. Also you cannot compare a weak refcursor with normal cursor and they work differently. It's a buffer space which is allocated to hold the result temporarily. When you run the below statement in PLSQL block, PLSQL engine doesnot understand it a PLSQL variable and throws the error

for x in cur loop

PLS-00221: 'CUR' is not a procedure or is undefined

Apart the below statement will also fail since you didnot defined the OUT paramater to the Package if its retruning a SYS_REFCURSOR.

cur := PACKAGE.GetData(1234);

You can fetch the content of the SYS_REFCURSOR and then display it as below:

declare
  a  SYS_REFCURSOR;
  v_emp_id  employee.emp_id%type;
begin         
  --- This is a procedure with OUT parameter as SYS_REFCURSOR
  dynmc_selec(emp_output=>a);

  loop
    FETCH a INTO v_emp_id;
    EXIT WHEN a%NOTFOUND;
    DBMS_OUTPUT.PUT_LINE(v_emp_id );

  end loop;
end;

来源：https://stackoverflow.com/questions/42698175/pl-sql-for-loop-sys-refcursor

标签

plsql

oracle12c