Suggest idea for creating microsite in Joomla 1.5

I am having a site as http://www.test.com running in Joomla 1.5 . We are planning to have a microsite like http:开发者_开发技巧//www.sub.test.com which has to have separate homepage with different contents .

Is that is possible with the following idea

1. Making a export of all the tables in my joomla and replacing jos with suband again importing them into the same Joomla database.
2. Writing a PHP script of identifying whether the Url tat i have entered in the browser is http://www.test.com OR http://www.sub.test.com

If test.com, then the $dbprefix would be jos OR if sub.test.com then the $dbprefix would be sub.

Will the above idea for creating a microsite is the correct one.

Just as another option, you could contain both sites in the exact same instance with a different template assigned to the micro site.

Set up a content category for the micro site, detect the request URL (most likely in the WebServer - best location, or in a DNS setting with a forward URL)

Assign all content items in the category with the new Template.

We regularly do this for a site that wants a blog site alongside the main website, but want a different look and feel.