+++ Introduction In Doctrine all record relations are being set with {{hasMany}}, {{hasOne}}, {{ownsMany}} and {{ownsOne}} methods. Doctrine supports almost any kind of database relation from simple one-to-one foreign key relations to join table self-referencing relations. +++ Relation aliases Doctrine supports relation aliases through {{as}} keyword. class Forum_Board extends Doctrine_Record { public function setTableDefinition() { $this->hasColumn('name', 'string', 100); $this->hasColumn('description', 'string', 5000); } public function setUp() { // notice the 'as' keyword here $this->ownsMany('Forum_Thread as Threads', 'Forum_Thread.board_id'); } } class Forum_Thread extends Doctrine_Record { public function setTableDefinition() { $this->hasColumn('board_id', 'integer', 10); $this->hasColumn('updated', 'integer', 10); $this->hasColumn('closed', 'integer', 1); } public function setUp() { // notice the 'as' keyword here $this->hasOne('Forum_Board as Board', 'Forum_Thread.board_id'); } } $board = new Board(); $board->Threads[0]->updated = time(); +++ Foreign key associations +++ Join table associations +++ Inheritance +++ Foreign key constraints