獲取每個時間行的計數出現在兩個日期之間的範圍

Question

我試圖計算一行中「出現」a在兩個日期之間的範圍內並將其按月份分組的次數。

所以，讓我們說，我有看起來像這樣的行：

Name | StartDate  | EndDate 
-----------|-----------------|------------ 
    Mathias | 2017-01-01  | 2017-04-01 
    Lucas | 2017-01-01  | 2017-04-01 

我想獲得，顯示多少條記錄在查詢中兩個日期之間存在的輸出，所以像下面的輸出：

Count | Year   | Month 
-----------|-----------------|------------ 
    2  | 2017   | 1 
    2  | 2017   | 2 
    2  | 2017   | 3 
    2  | 2017   | 4 
    0  | 2017   | 5 
    0  | 2017   | 6 

我已經試過是：

SELECT COUNT(*) as COUNT, YEAR(StartDate) YEAR, MONTH(StartDate) MONTH 
FROM NamesTable 
WHERE Start >= '2017-01-01 00:00:00' 
AND Slut <= '2017-06-01 00:00:00' 
group by YEAR(StartDate), MONTH(StartDate) 

哪裏，這是給我的EXP ected輸出：

Count | Year   | Month 
-----------|-----------------|------------ 
    2  | 2017   | 1 
    0  | 2017   | 2 
    0  | 2017   | 3 
    0  | 2017   | 4 
    0  | 2017   | 5 
    0  | 2017   | 6 

由於分組由「開始日期」，我怎麼能算在本月行的每一個它擴展跨越？

Answer 1

你需要一個表的範圍幾個月

表allMonths

+---------+------------+------------+ 
| monthId | StartDate | EndDate | 
+---------+------------+------------+ 
|  1 | 2017-01-01 | 2017-01-02 | 
|  2 | 2017-01-02 | 2017-01-03 | 
|  3 | 2017-01-03 | 2017-01-04 | 
|  4 | 2017-01-04 | 2017-01-05 | 
|  5 | 2017-01-05 | 2017-01-06 | 
|  6 | 2017-01-06 | 2017-01-07 | 
|  7 | 2017-01-07 | 2017-01-08 | 
|  8 | 2017-01-08 | 2017-01-09 | 
|  9 | 2017-01-09 | 2017-01-10 | 
|  10 | 2017-01-10 | 2017-01-11 | 
|  11 | 2017-01-11 | 2017-01-12 | 
|  12 | 2017-01-12 | 2018-01-01 | 
+---------+------------+------------+ 

那麼你的查詢是：

SELECT am.startDate, COUNT(y.Name) 
FROM allMonths am 
LEFT JOIN yourTable y 
    ON am.StartDate <= y.EndDate 
AND am.EndDate >= y.StartDate 
GROUP BY am.startDate 

注：您需要檢查邊界情況。也許你需要更改>=至>或將EndDate更改爲月份的最後一天。

Answer 2

所以，我落得這樣做有點像胡安·卡洛斯提出，但不是創建一個表我CTE由它代替了一個更簡潔的方法：

Declare @todate datetime, @fromdate datetime, @firstOfMonth datetime, @lastOfMonth datetime 
Select 
@fromdate='2017-01-11', 
@todate='2017-12-21', 
@firstOfMonth = DATEADD(month, DATEDIFF(month, 0, @fromdate), 0), ----YEAR(@fromdate) + MONTH(@fromdate) + DAY(1), 
@lastOfMonth = DATEADD(month, ((YEAR(@fromdate) - 1900) * 12) + MONTH(@fromdate), -1) 

;with MonthTable (MonthId, StartOfMonth, EndOfMonth) as 
(
     SELECT MONTH(@firstOfMonth) as MonthId, @firstOfMonth as StartOfMonth, @lastOfMonth as EndOfMonth 
     UNION ALL 
     SELECT MONTH(DATEADD(MONTH, 1, StartOfMonth)), DATEADD(MONTH, 1, StartOfMonth), DATEADD(MONTH, 1, EndOfMonth) 
     FROM MonthTable 
     WHERE StartOfMonth <= @todate 
) 

SELECT am.StartOfMonth, COUNT(y.Start) as count 
FROM MonthTable am 
left JOIN clientList y 
    ON y.Start <= am.StartOfMonth 
    AND y.End >= am.EndOfMonth 
GROUP BY am.StartOfMonth