Sql 计算帽子戏法的数量，即连续3次获胜（1胜0负）

从结果中计算帽子戏法的数量。i、 例如，连续赢3场（此处

Result

1表示赢，0表示输）

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尽管我非常讨厌游标，但我想不出其他方法可以在SQL Server 2008中轻松实现这一点，因此您可以尝试以下方法：

Declare @count int = 0,
        @Streak int = 0,
        @Hattrick int = 0
Declare foobar cursor forward_only for Select Streak from Tablename

Open foobar

fetch next from foobar into @Streak

While @@FETCH_STATUS = 0
Begin
    If @Streak = 1
        Set @count = @count + 1
    else
        Set @count = 0
    if @count = 3
        begin
           Set @Hattrick = @Hattrick + 1
           Set @count = 0
        end

    Fetch next from foobar into @Streak
End

Select @Hattrick

对于SQL Server的更高版本，我将混合使用交叉应用和延迟。不幸的是，Lag仅在SQL Server 2014及以后版本中可用

SQL Fiddle：

对于SQL Server 2014，请使用交叉应用和延迟：

Select Sum(Hattrick) Hattricks

from

(Select Case when c.Streak = 1 and lag(c.Streak, 1,0) over (order by c.MatchNo) = 0 and lag(c.Streak, 2,0) over (order by c.MatchNo) = 0 then 1 else 0 end Hattrick

from @foobar f
Cross apply
(select case when f.Streak = 1 and Streak = 1 then 1 else 0 end Streak, MatchNo from @foobar where MatchNo = f.MatchNo - 1) b
Cross apply
(select case when b.Streak = 1 and Streak = 1 then 1 else 0 end Streak, MatchNo from @foobar where MatchNo = b.MatchNo - 1) c) Hat

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SQL Fiddle:

没有游标的另一种方式可能是这样的。这将6个连续连胜视为2个帽子戏法。要把它看作是一个单一的条带，我们需要把最终的<代码>和（连线）改为<代码>计数（连线）

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当streak=1时，这是否表示它是一个帽子戏法？1表示赢，0表示输，实际上这里的streak是一个结果。你如何定义帽子戏法？预期的输出是什么（样本输入如所示）。@ddsprasad那么，数据中的hatrick定义是什么？一行中的6个streak=1是否意味着两个独立的帽子戏法？有一种非光标方式，但它涉及到自连接表3次（使用“匹配”列上的连接基本上检查前2个连胜是1，前3个连胜是0）但这里的光标可能更整洁。是的，我尝试过，问题是它必须在3后重置计数。因此，如果你连续赢了6场，那么只有2个帽子戏法（2个3连胜）.我做了你所描述的，我努力让它在不使用滞后的情况下在第一组3之后重置。但是，连续6场胜利仍然是1场帽子戏法？这就是为什么你需要将前三场比赛设为0。连续6场胜利都是2场帽子戏法，因为帽子戏法是连续3场胜利，所以连续6场胜利将是2 x 3场胜利=2场帽子戏法或t这就是我对这个模棱两可的问题的理解。哈哈，也许如果op的问题不是那么模棱两可的话，我们真的会知道。如果他说得更清楚，那么我会相应地更新。

Select Sum(Hattrick) Hattricks

from

(Select Case when c.Streak = 1 and lag(c.Streak, 1,0) over (order by c.MatchNo) = 0 and lag(c.Streak, 2,0) over (order by c.MatchNo) = 0 then 1 else 0 end Hattrick

from @foobar f
Cross apply
(select case when f.Streak = 1 and Streak = 1 then 1 else 0 end Streak, MatchNo from @foobar where MatchNo = f.MatchNo - 1) b
Cross apply
(select case when b.Streak = 1 and Streak = 1 then 1 else 0 end Streak, MatchNo from @foobar where MatchNo = b.MatchNo - 1) c) Hat

DECLARE @StreakTable Table (MatchNo int, Match_date date, Name varchar(20), Streak int)

Insert into @StreakTable values
(1, '2015-04-08', 'Aditya',1),
(2, '2015-04-09', 'Aditya',1),
(3, '2015-04-10', 'Aditya',0),
(4, '2015-04-11', 'Aditya',0),
(5, '2015-04-12', 'Aditya',1),
(6, '2015-04-13', 'Aditya',1),
(7, '2015-04-14', 'Aditya',1)

;WITH CTE AS 
(
    SELECT MatchNo,Match_date,Name,Streak,
    ROW_NUMBER() OVER(PARTITION BY Name ORDER BY Match_date) -
    ROW_NUMBER() OVER(PARTITION BY Name,streak ORDER BY Match_date)num
    FROM @StreakTable
), CountStreak as 
(
    SELECT Name,COUNT(*)/3 Streak
    FROM CTE
    WHERE Streak = 1
    GROUP BY num,Name
    HAVING  COUNT(*) >= 3
)
SELECT Name,SUM(Streak) as TotalStreak
FROM CountStreak
GROUP BY Name