我有这个代码,但无法让它工作:
$character_set_array = array();
    $character_set_array[] = array('count' => 8, 'characters' => '0123456789');
    $temp_array = array();
    foreach ($character_set_array as $character_set) {
        for ($i = 0; $i < $character_set['count']; $i++) {
            $temp_array[] = $character_set['characters'][rand(0, strlen($character_set['characters']) - 1)];
        }
    }
    shuffle($temp_array);
    $pinstart = 'AA';
    $pinend = implode('', $temp_array);
    $newpin = $pinstart.$pinend;
function regenerate_pin($pin)
{   
    if ($PIN == 'PIN') { return ''; } else {
    $pin = mysql_real_escape_string($pin);  // SECURITY!
    $result = mysql_query("SELECT pin FROM pins WHERE pin='$pin' LIMIT 1");
    if(mysql_num_rows($result) == 0) {
        return 'This pin has already been used';
            } else {
        $sql = mysql_query("UPDATE pins SET pins='$newpin'"); 
        return "The pin has been regened, the new pin is '.$newpin.'";
             } }
}
基本上我试图让它做的是: - 从 HTML 输入框中获取 pin, - 检查 pin 是否存在于数据库中(有效) - 如果存在,将 $pin 替换为 $newpin 并打印出来$newpin,这就是我的桌子的样子

- 关于我的桌子的一些信息:
 - 表名 = 针脚 存储针脚的列名为针脚
 
感谢您的阅读,我希望我能找到一个快速的解决方案。