public static void ShowTrainersInCourse() { Console.Clear(); CourseDb cDb = new CourseDb(); TrainersPerCourseDb tpcDb = new TrainersPerCourseDb(); List <Course> courses = cDb.GetCourses(); if (courses.Count != 0) { Console.WriteLine("Please select a course by using its number on the list: \n"); ShowList(courses, "Courses"); bool result = Int32.TryParse(Console.ReadLine(), out int courseID); while (!result || (courseID < 1 || courseID > courses.Count)) { Console.Write($"Wrong input! Please select using numbers from 1 to {courses.Count} "); result = Int32.TryParse(Console.ReadLine(), out courseID); } Console.Clear(); List <Trainer> trainersPerCourse = tpcDb.GetTrainersPerCourse(courseID); ShowList(trainersPerCourse, $"Trainers Per This Course"); } else { Console.WriteLine("There are no trainers or courses yet"); } }