public void AddCallOrEmail(CallOrEmail c)
 {
     using (var context = new StudentsContext(_connectionString))
     {
         context.CallsOrEmails.Add(c);
         context.SaveChanges();
     }
 }
 public void AddStudent(Student Student)
 {
     using (var context = new StudentsContext(_connectionString))
     {
         context.Students.Add(Student);
         context.SaveChanges();
     }
 }
 public void AddContributionForStudent(int id, decimal amount)
 {
     using (var context = new StudentsContext(_connectionString))
     {
         Student student = context.Students.FirstOrDefault(s => s.Id == id);
         student.ContributionAmount = amount;
         context.SaveChanges();
     }
 }