问：CQN dbms_cq_notification.cq_notification_queryid

Question

什么是“dbms_cq_notification.cq_notification_queryid”在这个SELECT上做什么？我只是在学习CQN。我也相信mgr_id没有被使用或是吗？

DECLARE
  reginfo    cq_notification$_reg_info;
  mgr_id     NUMBER;
  dept_id    NUMBER;
  v_cursor   SYS_REFCURSOR;
  regid      NUMBER;
  qosflags   NUMBER;  

BEGIN
  qosflags := DBMS_CQ_NOTIFICATION.QOS_QUERY + DBMS_CQ_NOTIFICATION.QOS_ROWIDS;
  reginfo  := cq_notification$_reg_info('chnf_callback', qosflags,0, 0, 0);
  regid    := DBMS_CQ_NOTIFICATION.NEW_REG_START(reginfo);

  OPEN v_cursor FOR 
    SELECT DBMS_CQ_NOTIFICATION.CQ_NOTIFICATION_QUERYID, 
           manager_id
    FROM HR.employees
    WHERE employee_id = 7902;
  CLOSE v_cursor;

  OPEN v_cursor for
    SELECT DBMS_CQ_NOTIFICATION.CQ_NOTIFICATION_QUERYID, 
           department_id
    FROM HR.departments
    WHERE department_name = 'IT';
  CLOSE v_cursor;

  DBMS_CQ_NOTIFICATION.REG_END;
END;

我从这里{{3}}

取了它