In the framework jungle: Yii Basic Model

gistfile1.php

class User extends CActiveRecord {   

    public static function model($className=__CLASS__)
    {
        return parent::model($className);
    }
 
    public function relations()
    {
        return array(
            'posts' => array(self::HAS_MANY, 'Post', 'user_id'),
        );
    }

    public function rules()
    {
        return array(
            array('email, password', 'required'),
            array('email', 'email'),
            array('email','unique'),
            array('password', 'authenticate'),
            array('password','length','min'=>8,'max'=>45),
        );
    }
}

class Post extends CActiveRecord {

    public function rules()
    {
        return array(
            array('name, content', 'required'),
            array('name','length','min'=>3,'max'=>45),
            array('content','length','min'=>3,'max'=>2000),
        );
    }

    public function relations()
    {
        return array(
            'tags' => array(self::MANY_MANY, 'Tag', 'posts_tags(post_id, tag_id)'),
            'user' => array(self::BELONGS_TO, 'User', 'user_id')
        );
    }
}

class Tag extends CActiveRecord {

    public function relations()
    {
        return array(
            'posts' => array(self::MANY_MANY, 'Post', 'posts_tags(post_id, tag_id)'),
        );
    }
}