How do I have SubDomain and Multi-Tenant in Rails project.

Can anyone please expain me How do I have sub-domains and Multi-tenant database for each sub domain in Rails Application.

For an Example:-
I am having Multi-Tenant database for year wise record of hotels, but my requiremnt :-
star.hotel.com => multi-tenant database
blue.hotel.com => multi-tenant database

Thank You

Check one more time :-
star.hotel.com =>
2011 // tenant1
2012// tenant2
2013// tenant3

blue.hotel.com =>
2011//tenant1
2012//tenant2
2013//tenant3

I covered how you can do this with the Apartment gem as well as from scratch in these episodes: https://gorails.com/series/multitenancy-crash-course

Thank you Chris I will try to do the same, but getting error on root page.
www.lvh.me:3000 is redirected if account is not present and its not working please assist me.