Question

我遇到此错误：

注意：未定义变量：pdo in C：\ xampp \ htdocs \ islahPos \ pos \ posDash.php在第86行

致命错误：未捕获错误：调用成员函数prepare（） C：\ xampp \ htdocs \ islahPos \ pos \ posDash.php：86中的null堆栈跟踪：＃0 {main}在第86行的C：\ xampp \ htdocs \ islahPos \ pos \ posDash.php中抛出

请帮助我，我正在学习PHP

<div class="card-body p-0">
    <table class="table">
        <thead>
            <tr>
                <th style="width: 10px">#</th>
                <th>Name</th>
                <th>Password</th>
                <th>Phone No: </th>
            </tr>
        </thead>
        <tbody>
            <?php
            $select = $pdo->prepare("select * from users order by id desc");
            $select->execute();

            while($row=$select->fetch(PDO::FETCH_OBJ)) {
                echo '
                <tr> 
                    <td>'.$row->id.' </td>
                    <td> '.$row->email.' </td>
                    <td> '.$row->phone.'</td>
                    <td>'.$row->join_date.'</td>
                    <td> </td>
                </tr>
                ';
            }  
            ?>
        </tbody>
    </table>
</div>


Here is my database connection code


<?php
//initialize variables to hold connection parameters
$username = 'root';
$dsn = 'mysql:host=localhost; dbname=register';
$password = '';

try{
    //create an instance of the PDO class with the required parameters
    $db = new PDO($dsn, $username, $password);

    //set pdo error mode to exception
    $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    //display success message
    //echo "Connected to the register database";

}catch (PDOException $ex){
    //display error message
    echo "Connection failed ".$ex->getMessage();
}

Answer 1

我只是在您的代码上方添加了pdo连接，并且工作正常，我在您的代码之前添加了以下几行：

<?php
$servername = "localhost";
$username = "root";
$password = "";

try {
$pdo = new PDO("mysql:host=$servername;dbname=stack", $username, $password);
// set the PDO error mode to exception
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
echo "Connected successfully";
}
catch(PDOException $e)
{
echo "Connection failed: " . $e->getMessage();
}
?>

所以只需检查您的连接即可。

无法从数据库获取数据

1 个答案: