The PHP Data Objects (PDO) extension defines a lightweight, consistent interface for accessing databases in PHP. Each database driver that implements the PDO interface can expose database-specific features as regular extension functions. Note that you cannot perform any database functions using the PDO extension by itself; you must use a database-specific PDO driver to access a database server.
PDO_MYSQL is a driver that implements the PHP Data Objects (PDO) interface to enable access from PHP to MySQL 3.x and 4.x databases.
I referred the followings steps :
1) Download the PDO package to server :
2) Manually build and install the PDO extension:
# tar xzf PDO-0.2.tgz
# cd PDO-0.2
# make install
# echo extension=pdo.so >> /usr/local/lib/php.ini
3) rebuild PHP along with the drivers for PDO_mysql.
4) check php module using php -m command