public function exists()
{
return false !== Sdb::fetchRow('id', static::table(), $this->selfCond());
}
public static function check($username, $password)
{
$conds = array('username=? AND password=?' => array($username, md5($password)));
$info = Sdb::fetchRow('*', self::table(), $conds);
return $info ? new self($info) : false;
}
public function commentedByUser(User $user)
{
$conds = array('user=? AND teacher=?' => array($user->id, $this->id));
$id = Sdb::fetchRow('id', Comment::table(), $conds);
return $id ? new Comment($id) : false;
}
