将用户定义的函数修改为视图

Posted 2023-04-13

【中文标题】将用户定义的函数修改为视图

【英文标题】：modifying User Defined function into a view

【发布时间】：2013-08-16 17:46:46

【问题描述】：

我继承了一个用户定义的函数，我正在尝试修改并遇到了一些问题。我想将其修改为常规查询，然后将其变为视图。该函数是ufn_B2H_Enrolled_Clients_List。该函数拉取在选定时间段内注册程序的客户列表。 ufn_B2H_Enrolled_Clients_List 中有一个函数 ufn_B2H_STATUSES_THROUGH_DT 。这将选择客户在所选时间范围内的最大状态更改，因此如果客户注册然后取消注册然后再次注册，则该功能不会将它们纳入计数。

我想要的是获取 ufn_B2H_Enrolled_Clients_List 并将其转换为常规查询/视图，输出如下所示：

Total_Clients_Enrolled     Month    Year 
252                         1      2013
247                         2      2013
303                         3      2013




**ufn_B2H_Enrolled_Clients_List Function**

RETURNS varchar(100)
AS
BEGIN
      -- Declare the return variable here
      DECLARE @VALUE varchar(100)
      SELECT  @VALUE = VALUE 
      FROM ENUMS
      WHERE NAME = @NAME AND NUMBER = @NUMBER
      IF @VALUE IS NULL
            SET @VALUE = 'unknown'
      RETURN (@VALUE)
END

GO


CREATE FUNCTION [dbo].[ufn_B2H_Enrolled_Clients_List](@From_DT datetime, @To_DT datetime)
RETURNS @retB2H_Enrolled_Clients_List TABLE 
(
  CLT_NBR int
  )
AS 
BEGIN 
      INSERT INTO @retB2H_Enrolled_Clients_List
    --Include all clients enrolled prior to the period end date


      SELECT CLT_NBR
      FROM ECMS.dbo.ufn_B2H_STATUSES_THROUGH_DT(@To_DT) s1
      WHERE s1.B2H_STATUS=4 AND s1.Max_Effect_DT <DATEADD(d,1,@To_DT)
            --Exclude all clients disenrolled or transferred out prior to the start date
            EXCEPT
            SELECT s2.CLT_NBR
            FROM ECMS.dbo.ufn_B2H_STATUSES_THROUGH_DT(@To_DT) s2 JOIN ECMS.dbo.ufn_B2H_STATUSES_THROUGH_DT(@To_DT) s1 ON s1.CLT_NBR=s2.CLT_NBR
            WHERE s2.B2H_STATUS IN (7,9) AND s2.Max_Effect_DT <@From_DT AND s2.Max_Effect_DT>s1.Max_Effect_DT AND s1.B2H_STATUS IN (4,8)
                  --Exclude all clients who transferred in after the prior end date.
                  EXCEPT
                  SELECT s3.CLT_NBR
                  FROM ECMS.dbo.B2H_STATUS s3 JOIN ECMS.dbo.ufn_B2H_STATUSES_THROUGH_DT(@To_DT) s1 ON s1.CLT_NBR=s3.CLT_NBR
                  WHERE s3.B2H_STATUS = 8 AND s1.B2H_STATUS IN (4,8) AND s3.EFFECT_DT > @To_DT AND s3.Effect_DT>s1.Max_Effect_DT

RETURN
END

GO

CREATE FUNCTION [dbo].[ufn_B2H_STATUSES_THROUGH_DT](@Through_DT datetime)
RETURNS @retB2H_STATUSES_THROUGH_DT TABLE 
(
   CLT_NBR int
  ,B2H_STATUS int
  ,Max_EFFECT_DT datetime
  )
AS 
BEGIN 
   INSERT INTO @retB2H_STATUSES_THROUGH_DT
       S


       ELECT CLT_NBR
               ,B2H_STATUS
               ,MAX(EFFECT_DT) AS Max_Effect_DT
            FROM [ECMS].[dbo].[B2H_STATUS]
            WHERE EFFECT_DT<DATEADD(d,1,@Through_DT)
            GROUP BY CLT_NBR, B2H_STATUS

RETURN
END

GO

【参考方案1】：

因为dbo.ufn_B2H_Enrolled_Clients_List 函数有参数，您可以将其转换为内联UDF，因此：

CREATE FUNCTION [dbo].[ufn_B2H_Enrolled_Clients_List](@From_DT datetime, @To_DT datetime)
RETURNS TABLE 
AS 
RETURN
      SELECT CLT_NBR
      FROM ECMS.dbo.ufn_B2H_STATUSES_THROUGH_DT(@To_DT) s1
      WHERE s1.B2H_STATUS=4 AND s1.Max_Effect_DT <DATEADD(d,1,@To_DT)
            --Exclude all clients disenrolled or transferred out prior to the start date
            EXCEPT
            SELECT s2.CLT_NBR
            FROM ECMS.dbo.ufn_B2H_STATUSES_THROUGH_DT(@To_DT) s2 JOIN ECMS.dbo.ufn_B2H_STATUSES_THROUGH_DT(@To_DT) s1 ON s1.CLT_NBR=s2.CLT_NBR
            WHERE s2.B2H_STATUS IN (7,9) AND s2.Max_Effect_DT <@From_DT AND s2.Max_Effect_DT>s1.Max_Effect_DT AND s1.B2H_STATUS IN (4,8)
                  --Exclude all clients who transferred in after the prior end date.
                  EXCEPT
                  SELECT s3.CLT_NBR
                  FROM ECMS.dbo.B2H_STATUS s3 JOIN ECMS.dbo.ufn_B2H_STATUSES_THROUGH_DT(@To_DT) s1 ON s1.CLT_NBR=s3.CLT_NBR
                  WHERE s3.B2H_STATUS = 8 AND s1.B2H_STATUS IN (4,8) AND s3.EFFECT_DT > @To_DT AND s3.Effect_DT>s1.Max_Effect_DT

GO

内联UDF 是一个带参数的视图：

内联函数可以用来实现的功能 参数化视图。

参考：http://technet.microsoft.com/en-us/library/aa214762(v=sql.80).aspx