根据包括空值在内的最大条件获取唯一记录

Question

我需要取回一位玩家（仅限 A 级玩家）最近获胜日期的记录（一些获胜日期为空，但我们需要包括它们）但只选择他们最近游戏会话的最后一个位置.所以基本上按照这个顺序：得到他们的最大值 win_date （如果为空，仍然包括它们）> 从那里抓住他们的最大位置 > 从那里，只选择他们的最大值 game_session_id.

Table 玩家：

Badge_No    Name     Game_Session_ID    Place    Win_Date    Rank
565         Barry    012550             4        6/17/2021    A
565         Barry    003521             2        3/04/2021    A
565         Barry    003521             3        3/04/2021    A
565         Barry    003521             4        3/04/2021    A
565         Barry    003521             5        3/04/2021    A
565         Barry    095945             1        6/17/2021    A
101         Lee      065411             1                     A
018         Jess     001561             1        5/23/2020    A
018         Jess     002075             1        5/23/2020    A         
209         Linda    026541             2        5/06/2021    A
728         Perry    000940             1        1/23/2021    B

预期输出：

Badge_No    Name     Game_Session_ID    Place    Win_Date    Rank
565         Barry    012550             4        6/17/2021    A
101         Lee      065411             1                     A
018         Jess     002075             1        5/23/2020    A 
209         Linda    026541             2        5/06/2021    A

我的（错误）代码：

select distinct badge_no, 
       name, max(game_session_id) game_session_id, 
       max(place) place, max(win_date) win_date, rank
from players p
where not exists 
    (select 'x' from players p2 
      where p2.badge_no = p.badge_no and p.rank = 'B')
group by badge_no, name, rank

Answer 1

将 ROW_NUMBER 与适当的分区一起使用：

WITH cte AS (
    SELECT p.*, ROW_NUMBER() OVER (PARTITION BY Badge_No
                                   ORDER BY Win_Date DESC, Place DESC, Game_Session_ID DESC) rn
    FROM players p
    WHERE "Rank" = 'A'
)

SELECT Badge_No, Name, Game_Session_ID, Place, Win_Date, "Rank"
FROM cte
WHERE rn = 1;

Answer 2

select badge_no, name,
       max(game_session_id) keep (dense_rank last
                       order by win_date nulls first, place) as game_session_id,
       max(place) keep (dense_rank last order by win_date nulls first) as place,
       max(win_date) as win_date, rank
from   players
where  rank = 'A'
group  by badge_no, name, rank
;

如果您不熟悉 first / last 聚合函数（不用担心，您不会孤单！），您可能需要快速浏览一下文档以了解它的作用。

根据包括空值在内的最大条件获取唯一记录

Getting unique record based on max conditions including null values

sql

oracle

subquery

max

dense-rank