Rss feeds from two tables and to come on top the latest created in two tables

Rails
1

hii all

want to generate rss feeds from two tables and to come on top the
latest created in two tables

1st table

create table
CREATE TABLE content_masters (
id int(11) NOT NULL auto_increment,
image_path varchar(255) collate utf8_unicode_ci default NULL,
content_text text collate utf8_unicode_ci,
abstract_text varchar(700) collate utf8_unicode_ci default NULL,
title varchar(255) collate utf8_unicode_ci default NULL,
color varchar(255) collate utf8_unicode_ci default NULL,
parent_id int(11) default NULL,
promote int(11) default ‘0’,
promote_block varchar(255) collate utf8_unicode_ci default ‘N’,
draft_state varchar(255) collate utf8_unicode_ci default ‘N’,
order_no_article int(11) default NULL,
created_at datetime default NULL,
updated_at datetime default NULL,
photo_file_name varchar(255) collate utf8_unicode_ci default NULL,
photo_content_type varchar(255) collate utf8_unicode_ci default
NULL,
photo_file_size int(11) default NULL,
photo_updated_at datetime default NULL,
PRIMARY KEY (id)
) ENGINE=InnoDB AUTO_INCREMENT=29 DEFAULT CHARSET=utf8
COLLATE=utf8_unicode_ci

create table
CREATE TABLE sub_content_masters (
id int(11) NOT NULL auto_increment,
abstract_text varchar(700) collate utf8_unicode_ci default NULL,
title varchar(255) collate utf8_unicode_ci default NULL,
image_id varchar(255) collate utf8_unicode_ci default NULL,
order_no int(11) default NULL,
created_at datetime default NULL,
updated_at datetime default NULL,
PRIMARY KEY (id)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8
COLLATE=utf8_unicode_ci

want to join these two table in query
so that i got the latest created , title with abstract_text

my xml code
xml.instruct!

xml.rss “version” => “2.0”, “xmlns:dc” => “http://purl.org/dc/elements/
1.1/” do
xml.channel do

xml.title "Atlantis Software Articles "
xml.link url_for :only_path => false, :controller =>
‘articles’
xml.description “Atlantis Software Articles”

@articles.each do |article|
xml.item do
xml.title article.title
xml.link (root_url+article.title.gsub(/ /,‘-’).downcase)
xml.description article.content_text
end
end

@subcon.each do |article|
xml.item do
xml.title article.title
xml.description article.abstract_text
end
end

end
end

controller code
def rss
@articles = ContentMaster.find(:all, :order => “id DESC”)
@subcon = SubContentMaster.find(:all, :order => “id DESC”)
render :layout => false
response.headers[“Content-Type”] = “application/xml;
charset=utf-8”
end

pls help…

thanks

rahul