Model Class: D_Department_Course.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using SnapObjects.Data;
using DWNet.Data;
using Newtonsoft.Json;

namespace Appeon.ApiDoc.Models
{
    [DataWindow("d_department_course", DwStyle.Grid)]
    [Table("Course", Schema = "dbo")]
    [FromTable("Department", Schema = "dbo")]
    [FromTable("StudentGrade", Schema = "dbo")]
    #region DwSelectAttribute  
    [DwSelect("select Course.CourseID, Course.Title, Course.DepartmentID,Department.Name, " 
                  + "StudentGrade.StudentID, StudentGrade.Grade "
                  + "from Course, StudentGrade, Department where Course.CourseID = StudentGrade.CourseID "
                  + "and Course.DepartmentID = Department.DepartmentID")]
    #endregion
    [DwSort("course_departmentid A course_courseid A ")]
    [DwGroupBy(1, "course_departmentid")]
    [DwGroupBy(2, "course_courseid")]
    public class D_Department_Course
    {
        [DwColumn("CourseID")]
        public int Course_Courseid { get; set; }

        [DwColumn("Title")]
        public string Course_Title { get; set; }

        [DwColumn("DepartmentID")]
        public int Course_Departmentid { get; set; }

        [DwColumn("Name")]
        public string Department_Name { get; set; }

        [DwColumn("StudentID")]
        public int Studentgrade_Studentid { get; set; }

        [DwColumn("Grade")]
        public decimal? Studentgrade_Grade { get; set; }

    }

}