PHP+mysql实现从数据库获取下拉树功能示例

<?phpinclude "config.php";include "MySQL.php";$db = new Mysql('test'); //几个简单的类，不用列出来大家也看得懂。就是实例化一个数据库连接而已。function RootMenu ($PID,$n){global $arr,$db;$sql = "select * from menu where `PID` =$PID";$result = $db->query($sql);while ($i=$db->fetch_array($result)){  $i["TITLE"] =str_repeat('--',$n).$i["TITLE"];  $arr[] =$i;  RootMenu($i["ID"],($n+4));}return $arr;}$arr = RootMenu(0,0);?><select id=""><option value="0" selected="selected">请选择部门</option><?phpfor ($i=0;$i<count($arr);$i++) {?><option value="<?php echo $arr[$i]["ID"] ?>"><?php echo $arr[$i]["TITLE"] ?></option><?php }?></select>