Question

我收到此错误：必须声明标量变量“@ TempTable1”。如果我从@ Temptable1周围删除单引号但没有返回任何行，则查询有效。

    ALTER PROCEDURE dbo.StoredProcedure2
      @Studentcode int
    AS
      DECLARE @sql AS nvarchar(max)
      DECLARE @pivot_list AS nvarchar(max) -- Leave NULL for COALESCE technique
      DECLARE @select_list AS nvarchar(max) -- Leave NULL for COALESCE technique
      Declare @TempTable1 AS table(CourseTitel nvarchar(50) , Grade nvarchar(50))

      INSERT INTO @TempTable1 (CourseTitel, Grade) 
       SELECT Courses.CourseTitel, Status.Status 
       FROM Status 
         INNER JOIN Courses ON Status.CourseCode = Courses.CourseCode 
       WHERE (Status.StudentCode = @Studentcode)

      SELECT @pivot_list = COALESCE(@pivot_list + ', ','') + '[' + CONVERT(varchar, PIVOT_CODE) + ']',
             @select_list = COALESCE(@select_list + ', ','') + '[' + CONVERT(varchar, PIVOT_CODE) + '] AS [col_' + CONVERT(varchar, PIVOT_CODE) + ']'
      FROM (SELECT DISTINCT PIVOT_CODE 
            FROM (SELECT CourseTitel, Grade, ROW_NUMBER() OVER (PARTITION BY CourseTitel ORDER BY Grade) AS PIVOT_CODE 
                  FROM @TempTable1) 
            AS rows) 
      AS  PIVOT_CODES

    SET @sql = ';WITH p AS (SELECT CourseTitel, Grade, 
                ROW_NUMBER() OVER (PARTITION BY urseTitel ORDER BY Grade) AS PIVOT_CODE 
                FROM ' + @TempTable1 + ' ) SELECT CourseTitel, ' + select_list + '
                FROM p PIVOT (MIN(Grade)FOR PIVOT_CODE IN (' + @pivot_list + ')) AS pvt'
    --PRINT (@sql)
    EXEC (@sql)
    /* SET NOCOUNT ON */

Answer 1

因此，您要声明一个表变量，并尝试对其运行动态SQL。问题是使用exec或sp_executeSql完成的动态SQL基本上在其自己的作用域中运行，因此表变量不会在那里声明，并且随后不能在查询中使用。

我可以提出两种解决方法：

使表格可用作临时表格。由于临时表是真实表，因此可以在任何范围内访问它们，因此可以在动态sql中访问它们。一些伪tsql会像：

...
if object_id('tempdb..#TempTable1 ') is not null
  drop table #TempTable1 

create table #TempTable1 (CourseTitel nvarchar(50) , Grade nvarchar(50))
...
@sql = '... AS PIVOT_CODE FROM #TempTable1) SELECT CourseTitel...'

将表变量作为参数表格传递给动态sql块。这只适用于sql server 2008及更高版本。但是，这需要将表的结构定义为sql server类型。这可以在系统级别执行一次，例如：

CREATE TYPE TempTableType AS TABLE (CourseTitel nvarchar(50) , Grade nvarchar(50))

然后我们可以使用该类型声明表变量，并将其作为参数传递给动态sql

...
declare @TempTable1 AS TempTableType 
...
@sql = N'... AS PIVOT_CODE FROM @TempTable1) SELECT CourseTitel...'
EXEC sp_executesql @SQL, 
                   N'@TempTable1 TempTableType READONLY', 
                   @TempTable1 =@TempTable1

在存储过程中声明标量变量

1 个答案: