計算兩個日期之間每月的天數 - SQL

Question

我對SQL非常陌生，所以如果我使用了錯誤的術語，並且我編寫的代碼是可怕的，我很抱歉。

我試圖創建一個查詢來輸出每年每月的天數。我所創建的測試表datetest：

startdate enddate 
2105-12-16 2016-02-15 
2017-01-01 2017-01-02 

，並使用粘貼下面的查詢我得到如下結果：

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 
2015 31 15 0 0 0 0 0 0 0 0 0 16 
2017 4 0 0 0 0 0 0 0 0 0 0 0 

我遇到的問題是，當日期範圍變爲超過兩年結果落在開始日期年份而不是實際年份。

如果有人可以幫助我真的很感激它 感謝

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查詢

SELECT 
year(startdate) AS Year, 

SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(startdate), '-01-31') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(startdate), '-01-01') AS DATETIME),startdate))+1,0))+SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(enddate), '-01-31') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(enddate), '-01-01') AS DATETIME),startdate))+1,0)) AS "Jan", 

SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(startdate), '-02-28') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(startdate), '-02-01') AS DATETIME),startdate))+1,0))+SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(enddate), '-02-28') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(enddate), '-02-01') AS DATETIME),startdate))+1,0)) AS "Feb", 

SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(startdate), '-03-31') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(startdate), '-03-01') AS DATETIME),startdate))+1,0))+SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(enddate), '-03-31') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(enddate), '-03-01') AS DATETIME),startdate))+1,0)) AS "Mar", 

SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(startdate), '-04-30') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(startdate), '-04-01') AS DATETIME),startdate))+1,0))+SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(enddate), '-04-30') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(enddate), '-04-01') AS DATETIME),startdate))+1,0)) AS "Apr", 

SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(startdate), '-05-31') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(startdate), '-05-01') AS DATETIME),startdate))+1,0))+SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(enddate), '-05-31') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(enddate), '-05-01') AS DATETIME),startdate))+1,0)) AS "May", 

SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(startdate), '-06-30') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(startdate), '-06-01') AS DATETIME),startdate))+1,0))+SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(enddate), '-06-30') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(enddate), '-06-01') AS DATETIME),startdate))+1,0)) AS "Jun", 

SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(startdate), '-07-31') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(startdate), '-07-01') AS DATETIME),startdate))+1,0))+SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(enddate), '-07-31') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(enddate), '-07-01') AS DATETIME),startdate))+1,0)) AS "Jul", 

SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(startdate), '-08-31') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(startdate), '-08-01') AS DATETIME),startdate))+1,0))+SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(enddate), '-08-31') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(enddate), '-08-01') AS DATETIME),startdate))+1,0)) AS "Aug", 

SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(startdate), '-09-30') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(startdate), '-09-01') AS DATETIME),startdate))+1,0))+SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(enddate), '-09-30') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(enddate), '-09-01') AS DATETIME),startdate))+1,0)) AS "Sep", 

SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(startdate), '-10-31') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(startdate), '-10-01') AS DATETIME),startdate))+1,0))+SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(enddate), '-10-31') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(enddate), '-10-01') AS DATETIME),startdate))+1,0)) AS "Oct", 

SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(startdate), '-11-30') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(startdate), '-11-01') AS DATETIME),startdate))+1,0))+SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(enddate), '-11-30') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(enddate), '-11-01') AS DATETIME),startdate))+1,0)) AS "Nov", 

SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(startdate), '-12-31') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(startdate), '-12-01') AS DATETIME),startdate))+1,0))+SUM(GREATEST(datediff(least(CAST(CONCAT(YEAR(enddate), '-12-31') AS DATETIME),enddate),greatest(CAST(CONCAT(YEAR(enddate), '-12-01') AS DATETIME),startdate))+1,0)) AS "Dec" 

from datetest 

GROUP BY year(startdate) 

Answer 1

，所以我知道你不使用SQL服務器看着你的語法，所以這個概念可能會奏效對你而言，取決於你擁有的rdbms。但是，這個概念是創建一個兩個日期之間差異最大的統計表，然後使用它來加入原始表並將日期範圍扁平化爲單個行，然後簡單地將該信息轉回。

DECLARE @Table AS TABLE (startdate DATETIME, enddate DATETIME) 
INSERT INTO @Table (startdate, enddate) VALUES ('2015-12-16','2016-02-15'),('2017-01-01','2017-01-02') 

;WITH cteTally as (
    SELECT MAX(DATEDIFF(day,startdate,enddate)) - 1 as Tally 
    FROM 
     @Table 

    UNION ALL 

    SELECT Tally - 1 
    FROM 
     cteTally 
    WHERE 
     Tally - 1 >= 0 
) 

, cteDates AS (
    SELECT 
     DATEADD(day,c.Tally,t.startdate) as date 
     ,YEAR(DATEADD(day,c.Tally,t.startdate)) as [Year] 
     ,LEFT(DATENAME(month,DATEADD(day,c.Tally,t.startdate)),3) as [Month] 
    FROM 
     @Table t 
     INNER JOIN cteTally c 
     ON DATEDIFF(day,t.startdate,t.enddate) - 1 >= c.Tally 
) 

SELECT * 
FROM 
    cteDates 
    PIVOT (
     COUNT([date]) 
     for [Month] IN ([Jan],[Feb],[Mar],[Apr],[May],[Jun],[Jul],[Aug],[Sep],[Oct],[Nov],[Dec]) 
    ) p 

oracle，postgressql和sql-server支持這種類型的結構，其中mysql不會。