When installing MDB2, keep in mind that the MDB2 package does not include any database drivers, so these will need to be installed separately. MDB2 is stable, but as explained earlier, since the packages have different release cycles, the status of the package you plan to use may be beta, alpha, or still in development. This will need to be taken into consideration when installing a driver package.

The easiest way to install MDB2 is by using the PEAR installer:

> pear install MDB2

This command will install the core MDB2 classes, but none of the database drivers. To install the driver for the database you’ll be using, type:

> pear install MDB2_Driver_mysql

This will install the driver for MySQL. If you wish to install the driver for SQLite, type:

> pear install MDB2_Driver_sqlite

The full list of currently available drivers is as follows:

fbsql: FrontBase

ibase: InterBase

mssql: MS SQL Server

mysql: MySQL

mysqli: MySQL using the mysqli PHP extension; for more details, visit http://php.net/mysqli oci8: Oracle

 

pgsql: PostgreSQL

querysim: Querysim

sqlite: SQLite

 

Source:
PHP PROGRAMMING WITH PEAR
XML, Data, Dates, Web Services, and Web APIs