I have a bus\_stops table with a one to one association with address table and address has a time zone attribute. 

Now when searching for stop timings, say all buses departing on 7 PM, this has to search for stops with buses departing on local time 7 PM, ie,

for each bus\_stop, I need to convert 7PM into local time zone of the bus stop depending on the time zone on address record. 

How would I achieve this using SQL (for postgres)