php - 解析错误 : syntax error, 意外 '$_GET' (T_VARIABLE)

Question

当我尝试从 URL 加载“id”时，它似乎不起作用。有什么理由吗？提前感谢您的帮助!

<?php

class Poll{

    private $db;
    private $presidentid = $_GET['id'];

    public function __construct($db){
        $this->db = $db;
    }

    public function getPollData(){
        $sql = "SELECT poll_question, yes, no FROM poll WHERE poll_id = $presidentid";
        $statement = $this->db->prepare($sql);
        $statement->execute();
        $pollData = $statement->fetchObject();
        return $pollData;
    }

}

?>

Answer 1

我们不会将变量放入准备好的查询中。

$sql = "SELECT poll_question, yes, no FROM poll WHERE poll_id = :id";

$statement = $this->db->prepare($sql);
$statement->bindParam(':id', $this->presidentid);
$statement->execute();

参见:http://php.net/manual/fr/pdo.prepare.php