add a dropdown box at header that shows cities

Hello everybody

I want to add a dropdown box at header that shows cities, and when a customer select a city the whole page get refreshed and just display that city products.

I mean when a city has been selected, all products that exist on that city get display.

My solution is that adding a new table and add a reference to the product table.
what is your idea about the solution and the coding behind that.
How can i accomplish this?


Please help me.

Thanks in advance