sql异常

DECLARE @temp TABLE
    (
      Id INT,
      Title nvarchar(50),
      Value    nvarchar(1000),
      Remark nvarchar(1000),
      Pass nvarchar(50)
    )  

   --获取自增最大值
   declare @flag int
   select @flag=Isnull(MAX(Id),0) from  AkWorkOrderPrintDate
   
   --变量
   while @flag>0
   begin
      --是否存在这条记录
      declare @count int
      select @count=COUNT(*) from AkWorkOrderPrintDate where Id=@flag
      if @count=1
      begin
        --拷贝这行的数据
        insert into @temp 
        select Id,Title,Value,Remark,‘值错误‘ from AkWorkOrderPrintDate where Id=@flag
        
        --测试日期设置
        declare @val nvarchar(1000)
        select @val=Value from @temp where Id=@flag
        set @val=‘select @a=‘+@val
        
        --执行
        begin try
          declare @pass nvarchar(1000)
          exec sp_executesql @val,N‘@a nvarchar(1000) output‘,@pass output 
  
          update @temp set Pass=@pass where Id=@flag
        end try
        begin catch
        end catch
      end
      set @flag=@flag-1
   end
   
   select * from @temp