<?php
$photoId = $_GET['photoId']; // 照片id
$albumId = $_GET['albumid']; // 相簿id
$page = 12; // 每頁張數

mysql_select_db($db);
$sql = sptintf("SELECT ph.*
	FROM album al 
	INNER JOIN photos ph ON ph.albumId = al.al_id AND al.al_id = %s 
	ORDER BY ph.ph_id ASC",
		$albumId);
$result = mysql_query($sql) or die(mysql_error());
$row = mysql_fetch_row($result);
$num = mysql_num_rows($result);

	// 將所有id寫入陣列
	do {
		$arrId[] = $row['ph_id'];
	} while($row = mysql_fetch_row($result));
	
	// 查出該照片在陣列的位置
	$position = array_search($photoId, $arrId)+1;
	
	// 若為末張修正正確頁數
	if ($position%$page == 0) {
		$pages = (int)($position/$page)-1;
	} else {
		$pages = (int)($position/$page);
	}
	
	return '<a href="album.php?pages=' . $pages . '&albumId=' . $albumId . '">回上層</a>';
	
mysql_free_result($result);
?>