sql - スカラー サブクエリ内のサブクエリがエラー ORA-00936 Missing Expression で失敗する

Question

1. これは機能しないクエリです。

   SELECT distinct ord.DateOrdered
      , (SELECT docno 
         FROM th_mm_c_orderline_history 
         WHERE th_mm_c_orderline_history_id 
               in (SELECT max(th_mm_c_orderline_history_id) 
                   FROM th_mm_c_orderline_history 
                   GROUP BY c_orderline_id ) 
         order by docno,c_orderline_id) as docno 
   FROM c_order ord 
   INNER JOIN c_orderline on c_orderline.c_order_id = ord.c_order_id 
   INNER JOIN th_mm_c_orderline_history 
         on th_mm_c_orderline_history.c_order_id=ord.c_order_id
   

   ORA-00936 Missing expression errorがスローされます

2. このクエリは正常に機能します。

   SELECT docno 
   FROM th_mm_c_orderline_history 
   WHERE th_mm_c_orderline_history_id 
         in (SELECT max(th_mm_c_orderline_history_id) 
             FROM th_mm_c_orderline_history 
             GROUP BY c_orderline_id ) 
   order by docno,c_orderline_id as docno