Propel is a full-service object persistence and query toolkit for PHP. It allows you to access your database using a set of objects, providing a simple API for storing and querying data. You might already have heard of this technique, but under a different name, like Data Access Objects (DAO) or Object Relational Mapping (ORM). It's a port of Apache Torque (see links section below).
Enterprise resource planning systems (ERPs) are management information systems that integrate and automate many of the business practices associated with the operations or production aspects of a company.