// Menu Insert Data

        public void InsertMenu()
        {
            string answer = string.Empty;

            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("\tMENU\n");
            Console.ForegroundColor = ConsoleColor.White;
            Console.WriteLine("\t1. Add new Course\n");
            Console.WriteLine("\t2. Add new Trainer\n");
            Console.WriteLine("\t3. Add new Assignment\n");
            Console.WriteLine("\t4. Add new Student\n");
            Console.Write("\t5. ");
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("Return to Main Menu\n");
            Console.ForegroundColor = ConsoleColor.White;
            Console.Write("\t0. ");
            Console.ForegroundColor = ConsoleColor.Cyan;
            Console.WriteLine("LogOut\n");
            Console.ForegroundColor = ConsoleColor.White;
            Console.Write("\tChoice : ");
            answer = StringAnswer();
            while (!(answer == "1" || answer == "2" || answer == "3" || answer == "4" || answer == "5" || answer == "0"))
            {
                Console.ForegroundColor = ConsoleColor.Red;
                Console.WriteLine("\tChoose Between (1,2,3,4,5,0)");
                Console.Beep();
                Console.ForegroundColor = ConsoleColor.White;
                Console.Write("\tChoice : ");
                answer = StringAnswer();
            }
            switch (answer)
            {
            case "1":
                Console.Clear();
                Welcome();
                Course c = new Course();
                c.InitializeCourse();
                Courses.Add(c);
                c.PrintTheCourseEntry();
                ContinueAddingCourseOrNot();
                break;

            case "2":
                Console.Clear();
                Welcome();
                Trainer t = new Trainer();
                t.Initrainer();
                Trainers.Add(t);
                t.PrintTheTrainerEntry();
                ContinueAddingTrainerOrNot();
                break;

            case "3":
                Console.Clear();
                Welcome();
                Assignment a = new Assignment();
                a.InitializeAssignment();
                Assignments.Add(a);
                a.PrintTheAssignmentEntry();
                ContinueAddingAsOrNot();
                break;

            case "4":
                Console.Clear();
                Welcome();
                Student s = new Student();
                s.InitStudent();
                Students.Add(s);
                s.PrintTheStudentEntry();
                ContinueAddingStudOrNot();
                break;

            case "5":
                GobackStartmenu();
                break;

            case "0":
                LogOut();
                break;
            }
        }
        public DataBase()
        {
            Student s1  = new Student("Panos", "Rizos", new DateTime(1993, 04, 12), 300);
            Student s2  = new Student("Nikos", "Ioannou", new DateTime(1992, 05, 13), 1.555);
            Student s3  = new Student("Kostas", "Dimitriou", new DateTime(1991, 06, 14), 500);
            Student s4  = new Student("Giannis", "Arvanitis", new DateTime(1990, 07, 15), 600);
            Student s5  = new Student("Maria", "Apostolou", new DateTime(1990, 08, 16), 800);
            Student s6  = new Student("Panos", "Mixahl", new DateTime(1989, 09, 17), 900);
            Student s7  = new Student("Eleni", "Theodwrou", new DateTime(1979, 01, 18), 1.125);
            Student s8  = new Student("Kostas", "Papadopoulos", new DateTime(1996, 02, 20), 400);
            Student s9  = new Student("Mixalis", "Petrou", new DateTime(1993, 05, 21), 100);
            Student s10 = new Student("Petros", "Karagiannis", new DateTime(1991, 12, 03), 200);
            Student s11 = new Student("Nikos", "Gianou", new DateTime(1991, 12, 03), 200);
            Student s12 = new Student("Kostas", "Mixahl", new DateTime(1991, 12, 03), 200);
            Student s13 = new Student("Iosif", "Papapetrou", new DateTime(1991, 12, 03), 200);
            Student s14 = new Student("Pelopidas", "Euaggeliou", new DateTime(1991, 12, 03), 1.265);
            Student s15 = new Student("Eirini", "Kostopoulou", new DateTime(1991, 12, 03), 200);
            Student s16 = new Student("Danah", "Goranith", new DateTime(1991, 12, 03), 200);


            Students = new List <Student>()
            {
                s1, s2, s3, s4, s5, s6, s7, s8, s9, s10, s11, s12, s13, s14, s15, s16
            };



            Course c1 = new Course("CB8", "C#", "FullTime", new DateTime(2019, 01, 01), new DateTime(2019, 03, 31));
            Course c2 = new Course("CB8", "C++", "PartTime", new DateTime(2019, 01, 01), new DateTime(2019, 06, 29));
            Course c3 = new Course("CB9", "JAVA", "FullTime", new DateTime(2019, 03, 01), new DateTime(2019, 06, 30));
            Course c4 = new Course("CB9", "PHP", "PartTime", new DateTime(2019, 03, 01), new DateTime(2019, 09, 28));


            Courses = new List <Course>()
            {
                c1, c2, c3, c4
            };



            Assignment as1  = new Assignment("Individual", "PartA", new DateTime(2020, 01, 10), 30, 70);
            Assignment as2  = new Assignment("Begginers", "PartA", new DateTime(2020, 01, 20), 30, 70);
            Assignment as3  = new Assignment("Bootcamp", "PartB", new DateTime(2020, 02, 14), 40, 60);
            Assignment as4  = new Assignment("Individual", "PartB", new DateTime(2020, 02, 27), 40, 60);
            Assignment as5  = new Assignment("Bootcamp", "PartA", new DateTime(2020, 01, 29), 40, 60);
            Assignment as6  = new Assignment("Finall", "Full", new DateTime(2020, 03, 19), 50, 50);
            Assignment as7  = new Assignment("Individual", "Full", new DateTime(2020, 03, 17), 50, 50);
            Assignment as8  = new Assignment("Begginers", "PartB", new DateTime(2020, 02, 10), 50, 50);
            Assignment as9  = new Assignment("Team", "Full", new DateTime(2020, 03, 18), 50, 50);
            Assignment as10 = new Assignment("Begginers", "PartA", new DateTime(2020, 02, 12), 50, 50);
            Assignment as11 = new Assignment("Team", "Full", new DateTime(2020, 02, 17), 50, 50);
            Assignment as12 = new Assignment("Individual", "PartB", new DateTime(2020, 02, 03), 50, 50);

            Assignments = new List <Assignment>()
            {
                as1, as2, as3, as4, as5, as6, as7, as8, as9, as10, as11, as12
            };


            Trainer t1 = new Trainer("Ektoras", "Gkatzos", SelectSubject.OOP);
            Trainer t2 = new Trainer("Mixalis", "Gianou", SelectSubject.FrontEnd);
            Trainer t3 = new Trainer("Kostantinos", "Zitis", SelectSubject.FrontEnd);
            Trainer t4 = new Trainer("Gewrgios", "Pasparakis", SelectSubject.SQL);
            Trainer t5 = new Trainer("Nikos", "Pavlou", SelectSubject.OOP);

            Trainers = new List <Trainer>()
            {
                t1, t2, t3, t4, t5
            };



            List <Trainer> c1trainers = new List <Trainer>()
            {
                t1, t2, t4
            };
            List <Trainer> c2trainers = new List <Trainer>()
            {
                t2, t4, t5
            };
            List <Trainer> c3trainers = new List <Trainer>()
            {
                t3, t4, t5
            };
            List <Trainer> c4trainers = new List <Trainer>()
            {
                t1, t3, t4
            };



            TrainerPerCourse TPC1 = new TrainerPerCourse(c1, c1trainers);
            TrainerPerCourse TPC2 = new TrainerPerCourse(c2, c2trainers);
            TrainerPerCourse TPC3 = new TrainerPerCourse(c3, c3trainers);
            TrainerPerCourse TPC4 = new TrainerPerCourse(c4, c4trainers);


            trainerPerCourses = new List <TrainerPerCourse>()
            {
                TPC1, TPC2, TPC3, TPC4
            };



            List <Student> c1Students = new List <Student>()
            {
                s1, s2, s3, s4, s5, s6
            };
            List <Student> c2Students = new List <Student>()
            {
                s6, s7, s8, s9, s10, s3
            };
            List <Student> c3Students = new List <Student>()
            {
                s11, s12, s13, s14, s4, s5
            };
            List <Student> c4Students = new List <Student>()
            {
                s15, s16, s1, s2, s14
            };


            StudentPerCourse SPC1 = new StudentPerCourse(c1, c1Students);
            StudentPerCourse SPC2 = new StudentPerCourse(c2, c2Students);
            StudentPerCourse SPC3 = new StudentPerCourse(c3, c3Students);
            StudentPerCourse SPC4 = new StudentPerCourse(c4, c4Students);

            StudentPerCourses = new List <StudentPerCourse>()
            {
                SPC1, SPC2, SPC3, SPC4
            };



            List <Assignment> c1assignments = new List <Assignment>()
            {
                as1, as3, as4
            };
            List <Assignment> c2assignments = new List <Assignment>()
            {
                as5, as6, as7
            };
            List <Assignment> c3assignments = new List <Assignment>()
            {
                as8, as9, as10
            };
            List <Assignment> c4assignments = new List <Assignment>()
            {
                as11, as12
            };

            AssignmentsPerCourse ASPC1 = new AssignmentsPerCourse(c1, c1assignments);
            AssignmentsPerCourse ASPC2 = new AssignmentsPerCourse(c2, c2assignments);
            AssignmentsPerCourse ASPC3 = new AssignmentsPerCourse(c3, c3assignments);
            AssignmentsPerCourse ASPC4 = new AssignmentsPerCourse(c4, c4assignments);

            assignmentPerCourse = new List <AssignmentsPerCourse>()
            {
                ASPC1, ASPC2, ASPC3, ASPC4
            };
        }