Sometimes a hosting provider limits the number of available databases per account, or maybe you just want to keep things more organized rather than have a bunch of databases scattered everywhere Or Sometimes more than one WordPress installation is necessary on a single site and WPMU would be overkill,In any case, you will want to install multiple instances of WordPress, each one using the same database.

this is quite simple to do, but you must install WordPress manually in order for it to work properly. A majority of the one click installations (most common is Fantastico) do not allow you to specify the prefix to use and this is absolutely necessary to be met with success.

During the installation process*, when it comes time to modify your wp-config.php file (or on the WordPress config options screen), make sure that you change the default wp_ prefix to something different.



WordPress Config File => Change Prefix

When it comes time to install another blog using the same database, be sure to repeat the steps being certain to replace the wp_ prefix with something unique for the installation.

That's all ;)