1. PDO (PDB,a simplistic wrapper for PDO that is somewhat API compatible with PEAR’s DB)
  1. ADODb, a database abstraction library for PHP. There is also a Python version;
  1. MySqli,The mysqli extension allows you to access the functionality provided by MySQL 4.1 and above
  1. PEAR::MDB2,a merge of the PEAR DB and Metabase php database abstraction layers
  1. Zend_Db from Zend Framework