使用MySQL的PHP​​中帶有命名占位符的預准備語句出錯

Question

使用此代碼，我的網頁上出現了這些錯誤

Notice: Undefined variable: dbh in /home/danu2_cj3/public_html/lists.php on line 14

Fatal error: Call to a member function prepare() on a non-object in /home/danu2_cj3/public_html/lists.php on line 14

這是我正在使用的php代碼，第14行是此代碼中的第四行

<?php
/* Execute a prepared statement by binding PHP variables */
$member = $_SESSION['SESS_MEMBER_ID'];
$sth = $dbh->prepare('SELECT name
    FROM lists
    WHERE member_id = :member_id ');
$sth->bindValue(':member_id', $member, PDO::PARAM_INT);
$sth->execute();
?>

我正在嘗試顯示一堆行的數組，其中這些行中的一個字段應該與登錄會話的人的member_id匹配

這是頁面的完整代碼（top.php和bottom.php只是布局頁面）

<?php include ('top.php')?>
<h1>My Profile </h1>
<a href="lists.php">My Lists</a> | <a href="logout.php">Logout</a></br>
</br>
Please select list to view/delete
<?php include ("connect.php")?>
<?php
/* Execute a prepared statement by binding PHP variables */
$member = $_SESSION['SESS_MEMBER_ID'];
$sth = $dbh->prepare('SELECT name
    FROM lists
    WHERE member_id = :member_id ');
$sth->bindValue(':member_id', $member, PDO::PARAM_INT);
$sth->execute();
?>

<?php include ('bottom.php')?>

這是我的connect.php文件

<?php
$username = "mydb";
$password = "mydb";
$hostname = "host"; 

//connection to the database
$dbh = mysql_connect($hostname, $username, $password) 
 or die("Unable to connect to database");

//select a database to work with
$selected = mysql_select_db("mydb",$dbh) 
  or die("Could not select database");
?>

Answer 1

您可能應該將connection添加到數據庫或檢查connect.php connection設置是否正確

try 
{
    $dbh = new PDO($dsn, $user, $password);
} 
catch (PDOException $e) 
{
    echo 'Connection failed: ' . $e->getMessage();
}

這里的文件