For integrity reasons, MySQL no longer has a RENAME DATABASE command. I ran into an issue in my development environment recently where I needed to rename a database. It wasn’t particularly complex, but was a massive amount of data (~20G). Reading around a bit, a lot of people recommend dumping your data out using mysqldump and then re-importing into a new database. That can be really slow on large databases, but if you’re using InnoDB you have another option. RENAME TABLE allows you to specify database names, so you can do things like:

rename table old_db.table to new_db.table;

and the table and all of its content will move (without a slow copy).

Given you don’t have a bunch of extra triggers and things set up, this Ruby snippet will move everything for you:

require 'rubygems'
require 'active_record'

OLD_DB = 'old_db_name'
NEW_DB = 'new_db_name'

ActiveRecord::Base.establish_connection(:adapter => 'mysql2', :database => OLD_DB)
ActiveRecord::Base.connection.tables.each do |table|
  ActiveRecord::Base.connection.execute "RENAME TABLE #{OLD_DB}.#{table} TO #{NEW_DB}.#{table};"
end