MySql PDO与数据库的连接

Question

我正在学习PDO,我感到非常困惑,我在下面有这段代码,所有看起来都对我,但是我得到这个错误代码,我不知道我要做什么来解决它,请帮助我:

<?php
$hostname='localhost';
$username='root';
$password='';

try {
    $dbh = new PDO("mysql:host=$hostname;dbname=stickercollections",$username,$password);
    echo 'Connected to Database<br/>';

    $sql = "SELECT * FROM stickercollections";
foreach ($dbh->query($sql) as $row)
    {
    echo $row["collection_brand"] ." - ". $row["collection_year"] ."<br/>";
    }


    $dbh = null;
    }
catch(PDOException $e)
    {
    echo $e->getMessage();
    }
?> 

---

错误代码 : Invalid argument supplied for foreach() in /Applications/XAMPP/xamppfiles/htdocs/GOTSWAPMAIN/index.php on line 11

Answer 1

尝试增加错误模式:

<?php
$hostname='localhost';
$username='root';
$password='';

try {
    $dbh = new PDO("mysql:host=$hostname;dbname=stickercollections",$username,$password);

    $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); // <== add this line
    echo 'Connected to Database<br/>';

    $sql = "SELECT * FROM stickercollections";
foreach ($dbh->query($sql) as $row)
    {
    echo $row["collection_brand"] ." - ". $row["collection_year"] ."<br/>";
    }


    $dbh = null;
    }
catch(PDOException $e)
    {
    echo $e->getMessage();
    }
?> 

编辑: pdo.error-handling说,您也可以使用pdo.errorcode和pdostatement.errorcode(或类似)获取更多信息,但我认为抛出异常是处理错误连接,未解析主机等的更好方法.