public List<string> searchByPhone(string phone)
 {
     DatabaseService ds = new DatabaseService();
     if (ds.phoneExists(phone) == true)
         return ds.getContact(new string[] { phone }, "Phone");
     return null;
 }
 public List<string> searchByFullName(string firstName, string lastName) 
 {
     DatabaseService ds = new DatabaseService();
     if (ds.fullNameExists(firstName, lastName) == true)
         return ds.getContact(new string[]{firstName, lastName}, "Name");
         return null;
 }