计算 SQL 服务器中某个值连续出现的最大次数

Question

我有 table 球员、成绩和 ID：

Player | Result | ID
---------------
An     | W      | 1
An     | W      | 1
An     | L      | 0
An     | W      | 1
An     | W      | 1
An     | W      | 1
Ph     | L      | 0
Ph     | W      | 1
Ph     | W      | 1
Ph     | L      | 0
Ph     | W      | 1

A 'W' 的 ID 始终为 1，

我需要创建一个查询来计算每个玩家连续 'W' 的最大次数：

Player | MaxWinStreak
---------------------
An     | 3    
Ph     | 2

我尝试使用 Rows Unbounded Preceeding，但我只能让它计算 Ws 的最大总数，而不是连续计算

    Select
    t2.player
    ,max(t2.cumulative_wins) As 'Max'

    From

    (   Select 
            t.Player
            ,Sum(ID) Over (Partition By t.Result,t.player 
             Order By t.GameWeek Rows Unbounded Preceding) As cumulative_wins

        From
             t  

             ) t2

    Group By
    t2.player

我可以采用其他方法吗？

Answer 1

您需要一列来指定排序。 SQL 个表表示 个无序 个集合。在下面的查询中，? 代表这一列。

您可以使用行数的差异来获得每一次连胜：

select player, count(*) as numwins
from (select t.*,
             row_number() over (partition by player order by ?) as seqnum, 
             row_number() over (partition by player, result order by ?) as seqnum_r 
      from t
     ) t
where result = 'W'
group by player, (seqnum - seqnum_r);

然后您可以获得最大值：

select player, max(numwins)
from (select player, count(*) as numwins
      from (select t.*,
                   row_number() over (partition by player order by ?) as seqnum, 
                   row_number() over (partition by player, result order by ?) as seqnum_r 
            from t
           ) t
      where result = 'W'
      group by player, (seqnum - seqnum_r)
     ) pw
group by player;

计算 SQL 服务器中某个值连续出现的最大次数

Count max number of consecutive occurrences of a value in SQL Server

sql

sql-server

gaps-and-islands