How to generate short link in php

CREATE TABLE `links` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `url` varchar(255) DEFAULT NULL,
  `ctime` int(11) DEFAULT NULL,  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=111 DEFAULT CHARSET=UTF8;

<VirtualHost *:80>
    DocumentRoot "E:/project/short"
    ServerName d.cn    <Directory "E:/project/short">
        DirectoryIndex index.html index.php 
        AllowOverride All
        Order deny,allow
        Allow from all    </Directory>
</VirtualHost>
 
 
<VirtualHost *:80>
    DocumentRoot "E:/project/short"
    ServerName localhost    <Directory "E:/project/short">
        DirectoryIndex index.html index.PHP 
        AllowOverride All
        Order deny,allow
        Allow from all    </Directory>
</VirtualHost>

<IfModule mod_rewrite.c>RewriteEngine on
RewriteRule ^(\S{1,7})$ index.php?code=$1 [L]</IfModule>

<?php
function b64dec($b64) { //64进制转换成10进制
    $map = array(        &#39;0&#39;=>0,&#39;1&#39;=>1,&#39;2&#39;=>2,&#39;3&#39;=>3,&#39;4&#39;=>4,&#39;5&#39;=>5,&#39;6&#39;=>6,&#39;7&#39;=>7,&#39;8&#39;=>8,&#39;9&#39;=>9,
        &#39;A&#39;=>10,&#39;B&#39;=>11,&#39;C&#39;=>12,&#39;D&#39;=>13,&#39;E&#39;=>14,&#39;F&#39;=>15,&#39;G&#39;=>16,&#39;H&#39;=>17,&#39;I&#39;=>18,&#39;J&#39;=>19,
        &#39;K&#39;=>20,&#39;L&#39;=>21,&#39;M&#39;=>22,&#39;N&#39;=>23,&#39;O&#39;=>24,&#39;P&#39;=>25,&#39;Q&#39;=>26,&#39;R&#39;=>27,&#39;S&#39;=>28,&#39;T&#39;=>29,
        &#39;U&#39;=>30,&#39;V&#39;=>31,&#39;W&#39;=>32,&#39;X&#39;=>33,&#39;Y&#39;=>34,&#39;Z&#39;=>35,&#39;a&#39;=>36,&#39;b&#39;=>37,&#39;c&#39;=>38,&#39;d&#39;=>39,
        &#39;e&#39;=>40,&#39;f&#39;=>41,&#39;g&#39;=>42,&#39;h&#39;=>43,&#39;i&#39;=>44,&#39;j&#39;=>45,&#39;k&#39;=>46,&#39;l&#39;=>47,&#39;m&#39;=>48,&#39;n&#39;=>49,
        &#39;o&#39;=>50,&#39;p&#39;=>51,&#39;q&#39;=>52,&#39;r&#39;=>53,&#39;s&#39;=>54,&#39;t&#39;=>55,&#39;u&#39;=>56,&#39;v&#39;=>57,&#39;w&#39;=>58,&#39;x&#39;=>59,
        &#39;y&#39;=>60,&#39;z&#39;=>61,&#39;_&#39;=>62,&#39;=&#39;=>63
    );    $dec = 0;    $len = strlen($b64);    for ($i = 0; $i < $len; $i++) {        $b = $map[$b64{$i}];        if ($b === NULL) {            return FALSE;
        }        $j = $len - $i - 1;        $dec += ($j == 0 ? $b : (2 << (6 * $j - 1)) * $b);
    }    return $dec;
}function decb64($dec) { //10进制转换成64进制
    if ($dec < 0) {        return FALSE;
    }    $map = array(        0=>&#39;0&#39;,1=>&#39;1&#39;,2=>&#39;2&#39;,3=>&#39;3&#39;,4=>&#39;4&#39;,5=>&#39;5&#39;,6=>&#39;6&#39;,7=>&#39;7&#39;,8=>&#39;8&#39;,9=>&#39;9&#39;,
        10=>&#39;A&#39;,11=>&#39;B&#39;,12=>&#39;C&#39;,13=>&#39;D&#39;,14=>&#39;E&#39;,15=>&#39;F&#39;,16=>&#39;G&#39;,17=>&#39;H&#39;,18=>&#39;I&#39;,19=>&#39;J&#39;,
        20=>&#39;K&#39;,21=>&#39;L&#39;,22=>&#39;M&#39;,23=>&#39;N&#39;,24=>&#39;O&#39;,25=>&#39;P&#39;,26=>&#39;Q&#39;,27=>&#39;R&#39;,28=>&#39;S&#39;,29=>&#39;T&#39;,
        30=>&#39;U&#39;,31=>&#39;V&#39;,32=>&#39;W&#39;,33=>&#39;X&#39;,34=>&#39;Y&#39;,35=>&#39;Z&#39;,36=>&#39;a&#39;,37=>&#39;b&#39;,38=>&#39;c&#39;,39=>&#39;d&#39;,
        40=>&#39;e&#39;,41=>&#39;f&#39;,42=>&#39;g&#39;,43=>&#39;h&#39;,44=>&#39;i&#39;,45=>&#39;j&#39;,46=>&#39;k&#39;,47=>&#39;l&#39;,48=>&#39;m&#39;,49=>&#39;n&#39;,
        50=>&#39;o&#39;,51=>&#39;p&#39;,52=>&#39;q&#39;,53=>&#39;r&#39;,54=>&#39;s&#39;,55=>&#39;t&#39;,56=>&#39;u&#39;,57=>&#39;v&#39;,58=>&#39;w&#39;,59=>&#39;x&#39;,
        60=>&#39;y&#39;,61=>&#39;z&#39;,62=>&#39;_&#39;,63=>&#39;=&#39;,
    );    $b64 = &#39;&#39;;    do {        $b64 = $map[($dec % 64)] . $b64;        $dec /= 64;
    } while ($dec >= 1);    return $b64;
    
}

<?php
include &#39;func.php&#39;;define("HOST","localhost");define("DB_NAME","test");
define("USER","root");define("PASS","root"); 
function make_short_url($url){    $url=str_ireplace("http://","",$url);    
$pdo = new PDO("mysql:host=".HOST.";dbname=".DB_NAME,USER,PASS); 
    $rs = $pdo ->query("select id from links where url=&#39;".$url."&#39;");    
    $row = $rs -> fetch(); 
    if($row==false){        
    $pdo -> exec("insert into links(url,ctime) values(&#39;".$url."&#39;,&#39;".mktime()."&#39;)"); 
        $id=$pdo -> lastinsertid(); 
        return "http://d.cn/".decb64($id);
    }else{        return "http://d.cn/".decb64($row[&#39;id&#39;]);
    }
} 
function get_long_url($code){    
$pdo = new PDO("mysql:host=".HOST.";dbname=".DB_NAME,USER,PASS); 
    $rs = $pdo ->query("select url from links where id=&#39;".b64dec($code)."&#39;");    
    $row = $rs -> fetch(); 
    if($row==false){        print "链接错误";        exit;
    }else{        return "http://".$row[&#39;url&#39;];
    }
}//参数的接收与短链接返回部分if($_GET[&#39;code&#39;]){    
$code=trim($_GET[&#39;code&#39;],"/");    $url=get_long_url($code);    
if($url){        header("location:$url");
    }
}elseif($_GET[&#39;url&#39;]){    
$url=trim($_GET[&#39;url&#39;]);    
print make_short_url($url);
}