protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                DataTable dt = CourseBLL.GetAllCourse();
                ddl_choose_course.DataSource     = dt;
                ddl_choose_course.DataTextField  = "CourseName";
                ddl_choose_course.DataValueField = "CourseId";
                ddl_choose_course.DataBind();

                //DataTable dt1 = CourseBLL.GetAllCourseAssocWith();
                //ddl_associated_with.DataSource = dt1;
                //ddl_associated_with.DataTextField = "CourseAssociatedWith";
                //ddl_associated_with.DataValueField = "CourseId";
                //ddl_associated_with.DataBind();
            }
        }