public static void UpdateData()
 {
     try
     {
         using (var context = new NewDBContext())
         {
             Show("tochange");
             Console.WriteLine("Choose ID to update");
             var markId = int.Parse(Console.ReadLine());
             var row    = context.MarkList.Find(markId);
             if (row != null)
             {
                 Console.WriteLine("Would you like to change student name? (Y(yes)/N(no))");
                 if ((Console.ReadLine()).ToUpper() == "Y")
                 {
                     ShowStudentIdAndName();
                     Console.Write("new ID: ");
                     var studId = int.Parse(Console.ReadLine());
                     row.StudentId = studId;
                 }
                 Console.WriteLine("Would you like to change course? (Y(yes)/N(no))");
                 if ((Console.ReadLine()).ToUpper() == "Y")
                 {
                     ShowCourseIdAndName();
                     Console.Write("new course ID: ");
                     var courseId = int.Parse(Console.ReadLine());
                     row.CourseId = courseId;
                 }
                 Console.WriteLine("Would you like to change mark? (Y(yes)/N(no))");
                 if ((Console.ReadLine()).ToUpper() == "Y")
                 {
                     Console.Write("new mark from 2-4: ");
                     var point = int.Parse(Console.ReadLine());
                     row.Point = point;
                 }
                 if (context.SaveChanges() > 0)
                 {
                     Console.WriteLine("Data was successfully updated!");
                 }
                 else
                 {
                     Console.WriteLine("Fail! Data wasn't updated!");
                 }
             }
             else
             {
                 Console.WriteLine("Wrong mark ID!");
             }
         }
     }
     catch (Exception x)
     {
         Console.WriteLine($"Fail:{x.Message}");
     }
     finally
     {
         Console.WriteLine("Press any key to continue...");
         Console.ReadKey();
     }
 }
 public static void DeleteData()
 {
     try
     {
         using (var context = new NewDBContext())
         {
             Show("tochange");
             Console.Write("Choose ID to delete:");
             var markId = int.Parse(Console.ReadLine());
             var row    = context.MarkList.Find(markId);
             if (row != null)
             {
                 Console.Write("Are you sure? Y(yes)/N(no):");
                 var confirm = Console.ReadLine();
                 if (confirm.ToUpper() == "Y")
                 {
                     context.MarkList.Remove(row);
                 }
                 if (context.SaveChanges() > 0)
                 {
                     Console.WriteLine("Data was successfully deleted!");
                 }
                 else
                 {
                     Console.WriteLine("Fail! Data wasn't deleted!");
                 }
             }
             else
             {
                 Console.WriteLine("Wrong mark ID!");
             }
         }
     }
     catch (Exception x)
     {
         Console.WriteLine($"Fail:{x.Message}");
     }
     finally
     {
         Console.WriteLine("Press any key to continue...");
         Console.ReadKey();
     }
 }
        public static void AddData()
        {
            try
            {
                using (var context = new NewDBContext())
                {
                    Console.WriteLine("Choose Student id: ");
                    ShowStudentIdAndName();
                    var studId = int.Parse(Console.ReadLine());

                    Console.WriteLine("Choose Course id: ");
                    ShowCourseIdAndName();
                    var courseId = int.Parse(Console.ReadLine());

                    Console.WriteLine("Choose mark from 2-4:");
                    var point = int.Parse(Console.ReadLine());

                    MarkList newMark = new MarkList()
                    {
                        StudentId = studId,
                        CourseId  = courseId,
                        Point     = point
                    };
                    context.MarkList.Add(newMark);
                    var result = context.SaveChanges();
                    if (result > 0)
                    {
                        Console.WriteLine("New data was successfully added!");
                    }
                }
            }
            catch (Exception x)
            {
                Console.WriteLine($"Fail:{x.Message}");
            }
            finally
            {
                Console.WriteLine("Press any key to continue...");
                Console.ReadKey();
            }
        }