change_mysql_character_set_and_collation.rb

##Create a migration
### rails g migration make_unicode_friendly

class MakeUnicodeFriendly < ActiveRecord::Migration
  def change
    alter_database_and_tables_charsets "utf8", "utf8_general_ci"
  end

  private
  def alter_database_and_tables_charsets charset = default_charset, collation = default_collation
    case connection.adapter_name
      when 'Mysql2'
        execute "ALTER DATABASE #{connection.current_database} CHARACTER SET #{charset} COLLATE #{collation}"

        connection.tables.each do |table|
          execute "ALTER TABLE #{table} CONVERT TO CHARACTER SET #{charset} COLLATE #{collation}"
        end
      else
        # OK, not quite irreversible but can't be done if there's not
        # the code here to support it...
        raise ActiveRecord::IrreversibleMigration.new("Migration error: Unsupported database for migration to UTF-8 support")
    end
  end

  def default_charset
    case connection.adapter_name
      when 'Mysql2'
        execute("show variables like 'character_set_server'").fetch_hash['Value']
      else
        nil
    end
  end

  def default_collation
    case connection.adapter_name
      when 'Mysql2'
        execute("show variables like 'collation_server'").fetch_hash['Value']
      else
        nil
    end
  end

  def connection
    ActiveRecord::Base.connection
  end
end