如何在SQL Server中的表值函数中使用CTE语句

Question

我已经了解到某些版本的Microsoft OLE DB Provider for SQL Server(主要在Windows XP上)不支持WITH语句.所以,我决定将我的SQL语句移动到表值函数中,并从我的应用程序中调用它.现在,我被困住了.我应该如何使用该INSERT INTO声明WITH？这是我到目前为止的代码,但SQL Server不喜欢它... :-(

CREATE FUNCTION GetDistributionTable 
(
    @IntID int,
    @TestID int,
    @DateFrom datetime,
    @DateTo datetime
)
RETURNS 
@Table_Var TABLE 
(
    [Count] int, 
    Result float
)
AS
BEGIN
INSERT INTO @Table_Var ([Count], Result) WITH T(Result)
     AS (SELECT ROUND(Result - AVG(Result) OVER(), 1)
         FROM RawResults WHERE IntID = @IntID AND DBTestID = @TestID AND Time >= @DateFrom AND Time <= @DateTo)
SELECT COUNT(*) AS [Count],
       Result
FROM   T
GROUP  BY Result

    RETURN 
END
GO

Answer 1

您可以省略CTE(WITH语句),而是创建一个使用子查询的内联表值函数:

CREATE FUNCTION GetDistributionTable 
(
    @IntID int,
    @TestID int,
    @DateFrom datetime,
    @DateTo datetime
)
RETURNS TABLE
AS
RETURN  
(
    WITH cte AS
    (
        SELECT ROUND(Result - AVG(Result) OVER(), 1) Result
        FROM   RawResults 
        WHERE  IntID = @IntID 
        AND    DBTestID = @TestID 
        AND    Time >= @DateFrom 
        AND Time <= @DateTo    
    )

    SELECT  COUNT(*) AS [Count],
            Result
    FROM    cte
    GROUP  BY 
            Result
)
GO

表值函数中CTE的语法将是:

CREATE FUNCTION GetDistributionTable 
(
    @IntID int,
    @TestID int,
    @DateFrom datetime,
    @DateTo datetime
)
RETURNS TABLE
AS
RETURN  
(
    SELECT  COUNT(*) AS [Count],
            Result
    FROM    (
                 SELECT ROUND(Result - AVG(Result) OVER(), 1) Result
                 FROM   RawResults 
                 WHERE  IntID = @IntID 
                 AND    DBTestID = @TestID 
                 AND    Time >= @DateFrom 
                 AND Time <= @DateTo    
    ) t
    GROUP  BY 
            Result
)
GO

您的示例似乎是使用多语句TVF(插入和选择),当您有选择尝试使用内联TVF时,因为多语句TVF可以阻止查询优化器选择更好的执行计划(此处说明的性能差异)

Answer 2

像这样..

CREATE FUNCTION GetDistributionTable 
(
    @IntID int,
    @TestID int,
    @DateFrom datetime,
    @DateTo datetime
)
RETURNS 
@Table_Var TABLE 
(
    [Count] int, 
    Result float
)
AS
BEGIN
  WITH T 
    AS (    
        select Ticket_Id,COUNT(1) Result from 
        Customer_Survey
        group by MemberID,SiteId,Ticket_Id
   )
  INSERT INTO @Table_Var ([Count], Result)
  SELECT COUNT(*) AS [Count],
       Result
  FROM   T
  GROUP  BY Result
  RETURN 
END
GO