I'm designing a hotel reservation system for school and would like to add a
function to the database to remove hotel rooms from circulation based on a
yes/no check box in the table.

I currently have 3 entities the first being Guest which as the name states
is used to get track of all relevant guest information.

The second entity is Room which contains the following: Room Number, Rack
Rate, Date Refurbished, Date Cleaned, and a check box for Out of Service.

My third entity is a intersection between Guest and Room titled Stay. This
entity tracks the dates of the stay, any incidentals or discounts applied,
and of course which room the guest stayed in. In order to select the room I
have a drop down menu in the Stay with a 1:m relation between room and stay.
What I would like to happen is when the Out of Service check box is checked
it removes the room from the drop down box. I don't know if it's possible but
if it is any help would be appreciated.