Troubleshooting and Support - Mastering phpMyAdmin 3.1 for Effective MySQL Management - page 301

The required extension is contained in a file that can be named mysql.so or mysqli.
so on Linux or UNIX, or mysql.dll (maybe mysqli.dll ) on Windows. If our PHP
server comes from a software package, we can find and install another software
package—probably called php-mysql or php-mysqli . (The name is distribution
dependent.) Otherwise, we can compile our own PHP server with the appropriate
extension, as explained in the PHP documentation.
#2003 - Can't connect to MySQL server
This message indicates that the MySQL server is not running, or cannot be reached
from the web server. It can also be a socket (Linux/UNIX) or a named pipe
(Windows) configuration problem.
Socket problem (Linux/UNIX)
The socket configured in php.ini (an example of which is given below) does not
correspond to the socket of the running MySQL server.
mysql.default_socket = /tmp/mysql.sock
As a result, PHP cannot reach MySQL. We can change it to:
mysql.default_socket = /var/lib/mysql/mysql.sock
However, to be sure, we must find the exact location of this socket.
Named pipe problem (Windows)
This is a problem similar to that indicated above, but on Windows. It can be solved
by adjusting mysql.default_socket with the correct named pipe used to connect
locally to a MySQL server. For example:
mysql.default_socket = MySQL
MySQL said: Access denied
This error can be solved when we understand the relevant login parameters.
When using http authentication
We cannot use the web server security mechanism based on a .htaccess file and the
http authentication in config.inc.php together. As a workaround, use cookie as
the authentication type instead of http .