使用 cte 循环的每日快照表

Question

我需要每天有多少员工在某一天（定义为 Start_Date 和 End_Date 之间的@date）的每日快照，每个日期一行。

在某一时刻，以下脚本将返回所有每日快照，但它们均在单独的结果窗口中返回。我无法让查询组合所有结果以将每个新结果插入#PLEASEWORK。

我需要让下面的工作连续两天。它使用int 日期。我继承了这个问题，并正在构建一个日期表来解决这个问题。

CREATE TABLE #PLEASEWORK
(
    [Date] INT
    ,Division_Description VARCHAR (100)
    ,[Count] INT
)

DECLARE @cnt AS INT
DECLARE @DATE AS INT

SET @CNT = '20181001'

WHILE @cnt >= @DATE

BEGIN

SELECT @DATE = '20181031' - 1


TRUNCATE TABLE #PLEASEWORK
INSERT INTO #PLEASEWORK

SELECT
    @DATE [date]
    ,Division_Description
    ,COUNT(*) [Count]
--INTO #PLEASEWORK
FROM EmpMaster

WHERE
    ([Start_Date] <= @DATE
    AND Leaving_Date = 0)
    OR ([Start_Date] <= @DATE
    AND Leaving_Date > @DATE)

GROUP BY
    Division_Description


SET @cnt = @cnt + 1

CONTINUE


SELECT *

FROM #PLEASEWORK

END

Answer 1

您可以在一个查询中完成所有这些操作。这是一种方法（不是最有效的），但一个月应该没问题。

declare @DATESTART date = '20181001';
declare @DATEEND date = '20181031';

with dates as (
      select @DATESTART as dte
      union all
      select dateadd(day, 1, dte)
      from dates
      where dte < @DATEEND
     )
select d.dte, dd.Division_Description,
       (select count(*)
        from EmpMaster e
        where e.Division_Description = dd.Division_Description and
              e.start_date <= d.dte and
              (e.leaving_date >= d.dte or e.leaving_date is null)
       ) as num_employees
from dates d cross join
     (select distinct Division_Description from EmpMaster) dd
order by d.dte, dd.Division_Description;

使用EmpMaster(Division_Description, start_date, leaving_date) 上的索引，这应该比基于游标的方法好得多。