There were some changes in PHP 5 regarding
databases (MySQL and SQLite).
In PHP 5 the MySQL client libraries are not
bundled, because of license and maintenance problems. MySQL is
supported with the only change being that MySQL support is no
longer enabled by default in PHP 5. This
essentially means that PHP doesn’t include the –with-mysql option in the configure line so that you
must now manually do this when compiling PHP. Windows users will
need to edit php.ini and enable the
php_mysql.dll DLL as in PHP 4 no such
DLL existed, it was simply built into your Windows PHP
There is also a new extension, MySQLi (Improved MySQL), which
is designed to work with MySQL 4.1 and above.
Since PHP 5, the SQLite extension is built-in PHP. SQLite is an
embeddable SQL database engine and is not a client library used to
connect to a big database server (like MySQL or PostgreSQL). The
SQLite library reads and writes directly to and from the database
files on disk.