What is PDO

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.

PDO is a lean, consistent way to access databases. This means developers can write portable code much easier. PDO is not an abstraction layer like PearDB. PDO is a more like a data access layer which uses a unified API (Application Programming Interface).

Drupal provides a database abstraction layer, which helps the developer to work easily with multi-database servers. It is used to preserve the syntax and power of SQL and to work with complex functionality. It provides a defined interface for dynamic queries with using security checks and good practices. This process is developed at the top of the PDO database API.

How to enable PDO

To enable PDO, configure --enable-pdo and --with-pdo-sqlite --with-pdo-mysql or whatever database needs supporting by PDO (see the PHP manual for more information).