在相同的CodeIgniter 2.x应用程序上使用多个数据库并使用URI路由发出问题

I am working on a small web application. In my application I follow the following approach.

Small overview of system

1. The Application will be hosted on the server for example (www.example.com )
2. Clients such as Microsoft, Cocacola, IBM.... etc will sign up. And the clients will access the application by using url like this ( www.example.com/ibm )
3. Each client will have separate database to store their data.

4. If the employees of the client want to login into the system then the url pattern should be like this :

   (www.example.com/ibm/user/login)
   ibm - is the client
   user - is controller
   login - is method of user controller

How to achieve this?

Thanks Sundar for your advice. We can achieve this just by little hack in core of codeigniter.

1. Open system/core/router.php in your text editor.
2. Go to Line number 264 .... function _validate_request($segments)
3. Replace $segments[0] with $segments[1] OR

4. Add this code at line 270

   $x=$segments; $a=1; for($i=0;$i<(count($segments)-1); $i++) { $segments[$i]=$x[$a]; $a++; }