$this->addTables( 'page_restrictions' );
$this->addWhere( 'page_id=pr_page' );
$this->addWhere( "pr_expiry > {$db->addQuotes( $db->timestamp() )} OR pr_expiry IS NULL" );
$this->addTables( 'page_restrictions' );
$this->addWhere( 'page_id=pr_page' );
$this->addWhere( "pr_expiry > {$db->addQuotes( $db->timestamp() )} OR pr_expiry IS NULL" );