计算2个日期之间每个日期的记录数

Question

我必须针对多轴图表的 return 结果创建查询。我需要计算为 2 个日期之间的每个日期创建的 ID 数。我试过这个：

 DECLARE @StartDate datetime2(7) = '11/1/2020',
         @EndDate datetime2(7) = '2/22/2021'

 ;WITH Date_Range_T(d_range) AS 
     (
       SELECT DATEADD(DAY, DATEDIFF(DAY, 0, @EndDate) - @StartDate, 0) 
       UNION ALL SELECT DATEADD(DAY, 1, d_range) 
       FROM Date_Range_T 
       WHERE DATEADD(DAY, 1, d_range) < @EndDate
     )

  SELECT d_range, COUNT(Id) as Total 
  FROM Date_Range_T 
       LEFT JOIN [tbl_Support_Requests] on ([tbl_Support_Requests].CreatedDate Between @StartDate AND @EndDate) 
  GROUP BY d_range ORDER BY d_range ASC

当然，问题出在 ;WITH 上，return 是错误

Operand type clash: datetime2 is incompatible with int.

如果我给它从当前日期起的特定天数，上面的方法就可以工作，比如：

 ;WITH Date_Range_T(d_range) AS 
 (
   SELECT DATEADD(DAY, DATEDIFF(DAY, 0, GETDATE()) - 6, 0) 
   UNION ALL SELECT DATEADD(DAY, 1, d_range) 
   FROM Date_Range_T 
   WHERE DATEADD(DAY, 1, d_range) < GETDATE()
 )

哪个 returns:

问题是我不知道如何替换日期范围。

Answer 1

不需要重新发明轮子 - 有很多递归 CTE 日历表的例子，类似于下面。

DECLARE @StartDate date = '01-Nov-2020', @EndDate date = '22-Feb-2021';

WITH Date_Range_T (d_range) AS (
    SELECT @StartDate AS d_range
    UNION ALL
    SELECT DATEADD(DAY, 1, d_range) 
    FROM Date_Range_T 
    WHERE DATEADD(DAY, 1, d_range) < @EndDate
)
SELECT d_range, COUNT(Id) AS Total 
FROM Date_Range_T 
LEFT JOIN tbl_Support_Requests R ON R.CreatedDate = d_range
GROUP BY d_range
ORDER BY d_range ASC
-- Set to the max number of days you require
OPTION (MAXRECURSION 366);

评论：

为什么要用 datetime2 代替 date？
您确定要 < 结束日期还是 <=？
您是否熟悉 between 的工作原理 - 它并不总是直观的。
为所有表格设置别名以提高可读性。
分号终止所有语句。
一致的大小写使查询更易于阅读。
对日期字符串使用明确的日期格式。

Answer 2

改进，我建议您使用计数 table 或函数，因为这通常性能更高。

我在下面使用了 Itzik Ben-Gan 的 well-known one：

DECLARE @StartDate date = '2020-11-01', @EndDate date = '2021-02-22';

  WITH
    L0 AS ( SELECT 1 AS c 
            FROM (VALUES(1),(1),(1),(1),(1),(1),(1),(1),
                        (1),(1),(1),(1),(1),(1),(1),(1)) AS D(c) ),
    L1 AS ( SELECT 1 AS c FROM L0 AS A CROSS JOIN L0 AS B ),
    L2 AS ( SELECT 1 AS c FROM L1 AS A CROSS JOIN L1 AS B ),
    Nums AS ( SELECT ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) AS rownum
              FROM L2 )
    Date_Range_T (d_range) AS (
      SELECT TOP(DATEDIFF(day, @StartDate, @EndDate) + 1)
          DATEADD(day, rownum - 1, @StartDate) AS d_range,
          DATEADD(day, rownum, @StartDate) AS d_rangeNext
      FROM Nums
    )
SELECT d_range, COUNT(Id) AS Total 
FROM Date_Range_T 
LEFT JOIN tbl_Support_Requests R
    ON R.CreatedDate >= T.d_range AND R.CreatedDate < T.d_rangeNext
GROUP BY d_range
ORDER BY d_range ASC

计算2个日期之间每个日期的记录数

Calculate the number of records for each date between 2 dates

sql

sql-server

tsql

date-range