You're mixing MySQL functions, you can't do that.
You're using mysql_query
and other mysql_
functions but with a mysqli_
DB connection.
Change $result = mysql_query($query) or die(mysql_error());
to
$result = mysqli_query($con,$query) or die(mysqli_error());
and while($row=mysql_fetch_assoc($result)){
to
while($row=mysqli_fetch_assoc($result)){
Plus, as stated in Notulysses' answer:
change $emp.loadCombo();
to $emp->loadCombo();