PEAR::DB is a database abstraction layer providing:
* an OO-style query API
* portability features that make programs written for one DBMS work with other
DBMS's
* a DSN (data source name) format for specifying database servers
* prepare/execute (bind) emulation for databases that don't support it natively
* a result object for each query response
* portable error codes
* sequence emulation
* sequential and non-sequential row fetching as well as bulk fetching
* formats fetched rows as associative arrays, ordered arrays or objects
* row limit support
* transactions support
* table information interface
* DocBook and phpDocumentor API documentation

Drivers for the following extensions pass the complete test suite and provide
interchangeability when all of DB's portability options are enabled: fbsql, 
ibase, informix, msql, mssql, mysql, mysqli, oci8, odbc, pgsql, sqlite and
sybase.

WWW: http://pear.php.net/package/DB/