To install the mysqli extension for PHP, use the
--with-mysqli=mysql_config_path/mysql_config
configuration option where mysql_config_path represents
the location of the mysql_config program that comes
with MySQL versions greater than 4.1.

If you would like to install the mysql extension along with the mysqli extension
you have to use the same client library to avoid any conflicts.

The default TCP port number to use when connecting to
the database server if no other port is specified. If
no default is specified, the port will be obtained
from the MYSQL_TCP_PORT environment
variable, the mysql-tcp entry in
/etc/services or the compile-time
MYSQL_PORT constant, in that order. Win32
will only use the MYSQL_PORT constant.

Allow interactive_timeout seconds (instead of wait_timeout seconds) of inactivity before closing the connection. The client's session wait_timeout variable will be set to the value of the session interactive_timeout variable.