public void ExecuteInsert(string[] commandWords) { string[] cW = commandWords; if (cW[5] == "course") { string courseName = cW[6]; string courseId = cW[7]; ICourse courseToInsertInto = null; foreach (var currentCourse in Course.CourseList) { if (currentCourse.CourseName.ToLower() == courseName.ToLower() && currentCourse.Id == ulong.Parse(courseId)) { courseToInsertInto = currentCourse; } } switch (cW[1]) { case "student": string studentName = cW[2]; string studentId = cW[3]; CourseParticipant studentToInsert; foreach (var currentStudent in Person.GetAllClients()) { if (currentStudent.FirstName.ToLower() == studentName.ToLower() && currentStudent.Id == ulong.Parse(studentId)) { studentToInsert = (CourseParticipant)currentStudent; courseToInsertInto.AddStudentToCourse(studentToInsert); } } break; case "teacher": string teacherName = cW[2]; string teacherId = cW[3]; Teacher teacherToInsert; foreach (var currentTeacher in Person.GetAllTeachers()) { if (currentTeacher.FirstName.ToLower() == teacherName.ToLower() && currentTeacher.Id == ulong.Parse(teacherId)) { teacherToInsert = (Teacher)currentTeacher; courseToInsertInto.AddTeachersToCourse(teacherToInsert); } } break; default: break; } } }