declare

  l_sql varchar2(123);        -- variable that contains a query

  l_c   sys_refcursor;        -- cursor variable(weak cursor).

  l_res your_table%rowtype;   -- variable containing fetching data

begin

  l_sql := 'select * from your_table';

  -- Open the cursor and fetching data explicitly

  -- in the LOOP.

  open l_c for l_sql;

  loop

    fetch l_c into l_res;

    exit when l_c%notfound;   -- Exit the loop if there is nothing to fetch.

     -- process fetched data 

  end loop;

  close l_c; -- close the cursor

end;