SQL

Question

I have two tables

table-1
Proproom_Id    PropReg_id    PropRoom Name


table-2
Propreg_id  propregname

and i have a combobox

how to write a sql query to bind a combobox on the click , propregname hase been binded already on click of propregname proproom name related to that has be bind

how to write sql query for that..?