复杂的分析函数语法格式简单描述如下：

    SELECT o_w_id, o_d_id, o_ol_cnt, o_entry_d, rank() OVER (PARTITION BY o_w_id order BY o_entry_d) entry_order 
      FROM ordr
     ORDER BY o_w_id , entry_order
) WHERE entry_order <=5;
SELECT * FROM (
    SELECT o_w_id, o_d_id, o_ol_cnt, o_entry_d, dense_rank() OVER (PARTITION BY o_w_id order BY o_entry_d) entry_order 
      FROM ordr
) WHERE entry_order <=5;
SELECT o_w_id, o_d_id, o_ol_cnt, o_entry_d, first_value(o_c_id) OVER (PARTITION BY o_w_id order BY o_entry_d) first_cid 
 ORDER BY o_w_id ;