Question

I’m getting this error:
Must declare the scalar variable “@TempTable1”.
The query works if i remove single quote from around @Temptable1 but no any rows returned.

    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

So you are declaring a table variable, and trying to run dynamic SQL against it. The problem is that dynamic SQL done with exec or sp_executeSql basically runs in its own scope, so the table variable is not declared there, and, subsequently cannot be used in a query.

I can propose two workarounds:

• Make the table available as a temporary table. Because the temp tables are real tables, they are accessible in any scope, so they will be accessible in the dynamic sql. Some pseudo-tsql would be like:

  ...
  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...'
  

• Pass the table variable to the dynamic sql block as a table valued parameted. This will only work in sql server 2008 and later. This however requires the structure of the table to be defined as a sql server type. This can be done once, on a system level, like:

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

  Then we can use that type to declare the table variable, and also, to pass it like a parameter to the dynamic sql

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