Question

我需要计算T-SQL中的累积计数。这可以这样做：

WITH DATASET AS (SELECT '2014-01-28' AS [DATE], 1 AS [COUNT]
UNION
SELECT '2014-01-29' AS [DATE], 5 AS [COUNT]
UNION
SELECT '2014-01-30' AS [DATE], 15 AS [COUNT]
UNION
SELECT '2014-01-31' AS [DATE], 4 AS [COUNT]
UNION
SELECT '2014-02-01' AS [DATE], 7 AS [COUNT]
UNION
SELECT '2014-02-02' AS [DATE], 1 AS [COUNT]
)
, CTE AS (SELECT *
,ROW_NUMBER() OVER (ORDER BY [DATE]) ROWNUM
FROM DATASET
)
SELECT CTE1.[DATE]
,CTE1.[COUNT]
,SUM(CTE2.[COUNT]) AS CUM_CNT
FROM CTE CTE1
JOIN CTE CTE2 ON CTE2.ROWNUM <= CTE1.ROWNUM
GROUP BY CTE1.[DATE]
,CTE1.[COUNT]

返回：

DATE        COUNT   CUM_CNT
2014-01-28      1        1
2014-01-29      5        6
2014-01-30     15       21
2014-01-31      4       25
2014-02-01      7       32
2014-02-02      1       33

但我想重置每个月的累积计数，因此返回的数据应为：

DATE        COUNT   CUM_CNT
2014-01-28      1        1
2014-01-29      5        6
2014-01-30     15       21
2014-01-31      4       25
2014-02-01      7        7
2014-02-02      1        8

是否可以在T-SQL中实现这一点？怎么样？

Answer 1

从SQL Server 2012+开始，您可以使用SUM的窗口版本来计算运行总计。您只需PARTITION YEAR([DATE]), MONTH([DATE])获得预期结果：

WITH DATASET AS (
SELECT '2014-01-28' AS [DATE], 1 AS [COUNT]
UNION
SELECT '2014-01-29' AS [DATE], 5 AS [COUNT]
UNION
SELECT '2014-01-30' AS [DATE], 15 AS [COUNT]
UNION
SELECT '2014-01-31' AS [DATE], 4 AS [COUNT]
UNION
SELECT '2014-02-01' AS [DATE], 7 AS [COUNT]
UNION
SELECT '2014-02-02' AS [DATE], 1 AS [COUNT]
)
SELECT [DATE], [COUNT], 
       SUM([COUNT]) OVER (PARTITION BY YEAR([DATE]), MONTH([DATE])
                          ORDER BY [DATE]) AS CUM_CNT
FROM DATASET

SQL Fiddle Demo

每月T-SQL累积计数重置

1 个答案: