Question

我有以下cte表达式，我尝试在动态sql中运行但是我收到了无效的标识符错误：

DECLARE @t TABLE ( ID INT, V float, D DATE )

INSERT  INTO @t
VALUES  ( 1, 1.2, '2014-01-01' ),
        ( 1, 1.33, '2014-01-02' ),
        ( 1, 1.33, '2014-01-03' ),
        ( 1, 7, '2014-01-04' ),
        ( 2, 5, '2014-01-04' ),
        ( 2, 8, '2014-01-10' ),
        ( 2, 11, '2014-01-05' );

DECLARE @DealClauseString nvarchar(max)
SET @DealClauseString =';WITH    filter
          AS ( SELECT   ID ,
                        D ,
                        V ,
                        ROW_NUMBER() OVER ( PARTITION BY ID ORDER BY D DESC ) AS RN
               FROM     @t where id =1
             ),
        cte
          AS ( SELECT   ID ,
                        D ,
                        V ,
                        MIN(D) OVER ( PARTITION BY ID ORDER BY D ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING ) AS Min ,
                        MAX(D) OVER ( PARTITION BY ID ORDER BY D ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING ) AS Max
               FROM     filter
               WHERE    RN <= 2
             )
    SELECT  c1.ID ,
            c2.V - c1.V AS V
    FROM    cte c1
            JOIN cte c2 ON c1.ID = c2.ID AND c1.D < c2.D
    WHERE   ( c1.D = c1.MIN OR c1.D = c1.MAX ) 
            AND ( c2.D = c2.MIN OR c2.D = c2.MAX ) '

exec @DealClauseString

有什么建议吗？

我还打算在while循环中运行这个cte表达式。在循环中运行cte表达式是否有任何性能问题？

Answer 1

首先，你不能use a table variable with dynamic sql，所以你应该使用#temp表，尽管这可能与你的示例代码有关。

其次，如果您使用的是动态sql，则需要将变量@DealClauseString放在括号中或使用sp_executesql，否则SQL Server assumes that you're calling a stored procedure。

CREATE TABLE #t ( ID INT, V FLOAT, D DATE )

INSERT  INTO #t
VALUES  ( 1, 1.2, '2014-01-01' ),
        ( 1, 1.33, '2014-01-02' ),
        ( 1, 1.33, '2014-01-03' ),
        ( 1, 7, '2014-01-04' ),
        ( 2, 5, '2014-01-04' ),
        ( 2, 8, '2014-01-10' ),
        ( 2, 11, '2014-01-05' );

DECLARE @DealClauseString NVARCHAR(MAX)
SET @DealClauseString = ';WITH    filter
          AS ( SELECT   ID ,
                        D ,
                        V ,
                        ROW_NUMBER() OVER ( PARTITION BY ID ORDER BY D DESC ) AS RN
               FROM     #t where id =1
             ),
        cte
          AS ( SELECT   ID ,
                        D ,
                        V ,
                        MIN(D) OVER ( PARTITION BY ID ORDER BY D ROWS 
                                      BETWEEN UNBOUNDED PRECEDING 
                                      AND UNBOUNDED FOLLOWING ) AS Min ,
                        MAX(D) OVER ( PARTITION BY ID ORDER BY D ROWS 
                                      BETWEEN UNBOUNDED PRECEDING AND 
                                      UNBOUNDED FOLLOWING ) AS Max
               FROM     filter
               WHERE    RN <= 2
             )
    SELECT  c1.ID ,
            c2.V - c1.V AS V
    FROM    cte c1
            JOIN cte c2 ON c1.ID = c2.ID AND c1.D < c2.D
    WHERE   ( c1.D = c1.MIN OR c1.D = c1.MAX ) 
            AND ( c2.D = c2.MIN OR c2.D = c2.MAX ) '

EXEC (@DealClauseString)

<强>结果：

ID  V
1   5.67

在动态sql中执行cte表达式

1 个答案: