PIVOT Dotaz na vícenásobné spojení

            DECLARE
            @columns NVARCHAR(MAX) = '',
            @columnsname NVARCHAR(MAX) = '',
            @columnsnameA NVARCHAR(MAX) = '',

            @columnsB NVARCHAR(MAX) = '',
            @columnsnameB NVARCHAR(MAX) = '',

            @sql     NVARCHAR(MAX) = '';

             -- select the question num
             SET @columns = STUFF((SELECT distinct ',' + QUOTENAME(cast(Question_no as varchar)) 
                        FROM submission1_details  WHERE Submission1_id=100

                        FOR XML PATH(''), TYPE
                        ).value('.', 'NVARCHAR(MAX)') 
                    ,1,1,'')

            SET @columnsname = STUFF((SELECT distinct ',' + QUOTENAME(cast(Question_no as varchar)) + ' sub1_Q'+ cast(Question_no as varchar)
                        FROM submission1_details  WHERE Submission1_id=100

                        FOR XML PATH(''), TYPE
                        ).value('.', 'NVARCHAR(MAX)') 
                    ,1,1,'')

                    SET @columnsnameA = STUFF((SELECT distinct ','+' sub1_Q'+ cast(Question_no as varchar)
                        FROM submission1_details  WHERE Submission1_id=100

                        FOR XML PATH(''), TYPE
                        ).value('.', 'NVARCHAR(MAX)') 
                    ,1,1,'')

                    SET @columnsB = STUFF((SELECT distinct ',' + QUOTENAME(cast(Question_no as varchar)) 
                        FROM submission2_details  WHERE Submission2_id=500

                        FOR XML PATH(''), TYPE
                        ).value('.', 'NVARCHAR(MAX)') 
                    ,1,1,'')

            SET @columnsnameB = STUFF((SELECT distinct ',' + QUOTENAME(cast(Question_no as varchar)) + ' sub2_Q'+ cast(Question_no as varchar)
                        FROM submission2_details  WHERE Submission2_id=500

                        FOR XML PATH(''), TYPE
                        ).value('.', 'NVARCHAR(MAX)') 
                    ,1,1,'')




            print @columns


             SET @sql ='
              select Submission1_id,Submission2_id,Name ,'+ @columnsnameA+ ','[email protected] +' from (
             select Submission1_id,Submission2_id,Name ,'[email protected]+',Question_no, Answer from (
             select distinct t1.Submission1_id,t1.Submission2_id,Name,t2.Question_no t,t2.Answer A,t3.Question_no,t3.Answer from submission1_header t1 
             inner JOIN submission1_details t2 ON  t1.Submission1_id=  t2.Submission1_id
              inner JOIN submission2_details t3 ON  t1.Submission2_id=  t3.Submission2_id  

             WHERE t1.Submission1_id=100
             ) as a
             PIVOT(
            MAX(A)
            for t  IN ('+ @columns +')
            ) AS pivot_table
            ) as b
            PIVOT(
            MAX(Answer)
            for Question_no  IN ('+ @columnsB +')
            ) AS pivot_table1;';
            print @sql

            -- execute the dynamic SQL
            EXECUTE sp_executesql @sql;