$criteria = new Criteria(); $criteria->addJoin(UserPeer::ID, PostPeer::USER_ID);
$criteria = new Criteria(); $criteria->addJoin(UserPeer::ID, PostPeer::USER_ID); $criteria->addJoin(PostPeer::ID, CommentPeer::POST_ID);This code joins the User, Post, and Comment tables together based on their relationships. Package Library: Propel ORM Library The Criteria addJoin method is commonly used in the Propel ORM library, which provides an easy to use, high-performance Object-Relational Mapping (ORM) layer for PHP. The addJoin method is part of the Criteria class in this library and allows developers to create complex database queries using simple-to-understand code.