How to get random number based on the condition.

[digituf]

i have two table in my database which is the room table and roomtype table.i'm using phpmyadmin.

room table
room_no
r_roomtypeID

roomtype table
roomtypeID
roomtype

how can i create a query that can select A random room_no from "room table "
based on the roomtypeID in the "table roomtype"

p/s - each roomtypeID got it's own quantity room no.

roomtypeID room_no

example : Single room : 1-10
: Deluxe room : 11-20
: Suite room : 21-30

right now i'm only having this kind of idea. the random number from room. I don't know how can i generate A random room_no from table room based on the roomtypeID.

(SELECT room_no FROM room ORDER BY RAND( )LIMIT 1)

any ideas is really appreciated:)