How Can I Fill Query Results Into Dataset Using Entity Framework

 public DataTable GetDepartmentsForSorting(DepartmentInfo _DepartmentInfo)
        {
            QuizEntity entity = new QuizEntity();
            DataTable dt = new DataTable();
            dt.Columns.Add("DeptID", typeof(double));
            dt.Columns.Add("DeptName", typeof(string));
            try
            {
                var a = entity.tblDepartments.AsQueryable();
                if (_DepartmentInfo.DeptName != string.Empty)
                {
                    a = a.Where(e => e.ClientID == _DepartmentInfo.ClientID && e.DeptName.Contains(_DepartmentInfo.DeptName)).OrderByDescending(e => e.DeptID);
                }
                else
                {
                    a = a.Where(e => e.ClientID == _DepartmentInfo.ClientID).OrderBy(e => e.DeptName);
                }
                
                foreach (var dr in a)
                {
                    DataRow row = dt.NewRow();

                    row.SetField<double>("DeptID", dr.DeptID);
                    row.SetField<string>("DeptName", dr.DeptName);

                    dt.Rows.Add(row);
                }
            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }
            finally
            {
                entity.Dispose();
            }
            return dt;
        }
</string></double>