mysql+php select ÏÂÀ­ÁбíÊ÷µÄ¼òµ¥ÊµÏÖ

Êý¾Ý¿âÉè¼Æ£º
--
-- Êý¾Ý¿â: `test`
--
-- --------------------------------------------------------
--
-- ±íµÄ½á¹¹ `menu`
--
CREATE TABLE IF NOT EXISTS `menu` (
`ID` int(10) unsigned NOT NULL auto_increment,
`PID` int(11) NOT NULL,
`TITLE` varchar(200) NOT NULL,
`REMARK` varchar(200) NOT NULL,
PRIMARY KEY (`ID`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=9 ;
--
-- µ¼³ö±íÖеÄÊý¾Ý `menu`
--
INSERT INTO `menu` (`ID`, `PID`, `TITLE`, `REMARK`) VALUES
(1, 0, '¹«Ë¾', '¸ù'),
(2, 1, '²ÆÎñ²¿', '²¿ÃÅ'),
(3, 1, 'ÏúÊÛ²¿', '²¿ÃÅ'),
(4, 1, 'ÈËʲ¿', ''),
(5, 2, '»á¼Æ', ''),
(6, 3, 'ÒµÎñÔ±', ''),
(7, 4, 'ÈËÊÂ×ܹÜ', '');
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PHP´úÂ룺
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<?php
include "config.php";
include "mysql.php";
$db = new Mysql('test'); //¼¸¸ö¼òµ¥µÄÀ࣬²»ÓÃÁгöÀ´´ó¼ÒÒ²¿´µÃ¶®¡£¾ÍÊÇʵÀý»¯Ò»¸öÊý¾Ý¿âÁ¬½Ó¶øÒÑ¡£
function RootMenu ($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;
} 
$arr = RootMenu(0,0);
?>
<select id="">
<option value="0" selected="selected">ÇëÑ¡Ôñ²¿ÃÅ</option>
<?php
for ($i=0;$i<count($arr);$i++) {
?>
<option value="<?php echo $arr[$i]["ID"] ?>"><?php echo $arr[$i]["TITLE"] ?></option>
<?php }?>
</select>
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