Combo box for registration

Hi dears, is possible to put a combo box in registration form?

For example: If a pilot select the airline “Iberia” automatically the hub will select “LEMD” in stead of the pilot can select. In other words the hub case will be lock (as a placeholder=“”)

How can I do it?

You should be able to do this with a php if statement:

if airline a then hub a, and go through the list. You can also hid the hub selection box by using the “hidden” attribute.

17 minutes ago, t_bergman said:

You should be able to do this with a php if statement:

if airline a then hub a, and go through the list. You can also hid the hub selection box by using the “hidden” attribute.

can you give an example?