您可以将COUNT DISTINCT与OVER子句一起使用吗？

        UPDATE  [#TempTable]
        SET     Received = r.Number
        FROM    [#TempTable] 
        INNER JOIN (SELECT  AgentID,
                            RuleID,
                            COUNT(DISTINCT (GroupId)) Number
                    FROM    [#TempTable]
                    WHERE   Passed = 1
                    GROUP BY AgentID,
                            RuleID
                   ) r ON r.RuleID = [#TempTable].RuleID AND
                          r.AgentID = [#TempTable].AgentID                            

CREATE CLUSTERED INDEX ix_test ON #TempTable(AgentID, RuleId, GroupId, Passed)

        WITH r AS (SELECT  AgentID,
                            RuleID,
                            COUNT(DISTINCT (GroupId)) Number
                    FROM    [#TempTable]
                    WHERE   Passed = 1
                    GROUP BY AgentID,
                            RuleID
            ) 
        UPDATE  [#TempTable]
        SET     Received = r.Number
        FROM    [#TempTable] 
        INNER JOIN r 
            ON r.RuleID = [#TempTable].RuleID AND
               r.AgentID = [#TempTable].AgentID                            

        UPDATE  [#TempTable]
        SET     Received = COUNT(DISTINCT (CASE WHEN Passed=1 THEN GroupId ELSE NULL END)) 
                    OVER (PARTITION BY AgentId, RuleId)
        FROM    [#TempTable] 

Msg 102, Level 15, State 1, Line 2
Incorrect syntax near 'distinct'.

DECLARE @Counting INT              
SELECT  @Counting = 1              

--  BEGIN:  Cascading Rule check --           
WHILE @Counting <= 30              
    BEGIN      

        UPDATE  w1
        SET     Passed = 1
        FROM    [#TempTable] w1,
                [#TempTable] w3
        WHERE   w3.AgentID = w1.AgentID AND
                w3.RuleID = w1.CascadeRuleID AND
                w3.RulePassed = 1 AND
                w1.Passed = 0 AND
                w1.NotFlag = 0      

        UPDATE  w1
        SET     Passed = 1
        FROM    [#TempTable] w1,
                [#TempTable] w3
        WHERE   w3.AgentID = w1.AgentID AND
                w3.RuleID = w1.CascadeRuleID AND
                w3.RulePassed = 0 AND
                w1.Passed = 0 AND
                w1.NotFlag = 1        

        UPDATE  [#TempTable]
        SET     Received = r.Number
        FROM    [#TempTable] 
        INNER JOIN (SELECT  AgentID,
                            RuleID,
                            COUNT(DISTINCT (GroupID)) Number
                    FROM    [#TempTable]
                    WHERE   Passed = 1
                    GROUP BY AgentID,
                            RuleID
                   ) r ON r.RuleID = [#TempTable].RuleID AND
                          r.AgentID = [#TempTable].AgentID                            

        UPDATE  [#TempTable]
        SET     RulePassed = 1
        WHERE   TotalNeeded = Received              

        SELECT  @Counting = @Counting + 1              
    END

#1 楼

SQL Server当前不支持此构造。它可以（并且应该在将来的版本中实现）。

应用反馈项中列出的报告此缺陷的变通办法之一，您的查询可以重写为：

WITH UpdateSet AS
(
    SELECT 
        AgentID, 
        RuleID, 
        Received, 
        Calc = SUM(CASE WHEN rn = 1 THEN 1 ELSE 0 END) OVER (
            PARTITION BY AgentID, RuleID) 
    FROM 
    (
        SELECT  
            AgentID,
            RuleID,
            Received,
            rn = ROW_NUMBER() OVER (
                PARTITION BY AgentID, RuleID, GroupID 
                ORDER BY GroupID)
        FROM    #TempTable
        WHERE   Passed = 1
    ) AS X
)
UPDATE UpdateSet
SET Received = Calc;

生成的执行计划是：



这具有避免为万圣节保护使用急切的表假脱机（ （由于自连接），但它引入了排序（针对窗口）和通常效率低下的惰性表假脱机构造，以计算SUM OVER (PARTITION BY)结果并将其应用于窗口中的所有行。在实践中，如何执行是一种练习，只有您才能执行。

总体方法很难使表现良好。递归地将更新（尤其是基于自联接的更新）应用于大型结构可能有助于调试，但这是导致性能下降的秘诀。反复进行大扫描，内存溢出和万圣节问题只是其中的一部分。索引和（更多）临时表可以提供帮助，但是需要非常仔细的分析，尤其是当索引由流程中的其他语句更新时（维护索引会影响查询计划的选择并添加I / O）。

最终，解决潜在的问题将使有趣的咨询工作变得有意义，但是对于此站点而言，这太过分了。我希望这个答案能解决表面问题。


原始查询的替代解释（导致更新更多行）：

WITH UpdateSet AS
(
    SELECT 
        AgentID, 
        RuleID, 
        Received, 
        Calc = SUM(CASE WHEN Passed = 1 AND rn = 1 THEN 1 ELSE 0 END) OVER (
            PARTITION BY AgentID, RuleID) 
    FROM 
    (
        SELECT  
            AgentID,
            RuleID,
            Received,
            Passed,
            rn = ROW_NUMBER() OVER (
                PARTITION BY AgentID, RuleID, Passed, GroupID
                ORDER BY GroupID)
        FROM    #TempTable
    ) AS X
)
UPDATE UpdateSet
SET Received = Calc
WHERE Calc > 0;

注意：取消排序（例如，通过提供索引）可能会重新引入对渴望的线轴或其他提供必要万圣节防护的需求。 Sort是一个阻塞运算符，因此可提供完全的相分离。

;WITH baseTable AS
(
              SELECT 'RM1' AS RM, 'ADR1' AS ADR
    UNION ALL SELECT 'RM1' AS RM, 'ADR1' AS ADR
    UNION ALL SELECT 'RM2' AS RM, 'ADR1' AS ADR
    UNION ALL SELECT 'RM2' AS RM, 'ADR2' AS ADR
    UNION ALL SELECT 'RM2' AS RM, 'ADR2' AS ADR
    UNION ALL SELECT 'RM2' AS RM, 'ADR3' AS ADR
    UNION ALL SELECT 'RM3' AS RM, 'ADR1' AS ADR
    UNION ALL SELECT 'RM2' AS RM, 'ADR1' AS ADR
    UNION ALL SELECT 'RM3' AS RM, 'ADR1' AS ADR
    UNION ALL SELECT 'RM3' AS RM, 'ADR2' AS ADR
)
,CTE AS
(
    SELECT RM, ADR, DENSE_RANK() OVER(PARTITION BY RM ORDER BY ADR) AS dr 
    FROM baseTable 
    -- Caveat: If there are NULL-values, add "WHERE ADR IS NOT NULL" here
)
SELECT
     RM
    ,ADR
    
    ,COUNT(CTE.ADR) OVER (PARTITION BY CTE.RM ORDER BY ADR) AS cnt1 
    ,COUNT(CTE.ADR) OVER (PARTITION BY CTE.RM) AS cnt2 
    -- Geht nicht / Doesn't work 
    --,COUNT(DISTINCT CTE.ADR) OVER (PARTITION BY CTE.RM ORDER BY CTE.ADR) AS cntDist
    ,MAX(CTE.dr) OVER (PARTITION BY CTE.RM ORDER BY CTE.RM) AS cntDistEmu 
FROM CTE