php - 未选择数据库 - php 和 phpmyadmin

Question

我正在尝试将我的 php 代码连接到我的数据库，一旦我在 html 表单中输入并提交了用户名、电子邮件地址和密码等内容。它们将被发送到我的数据库并显示在特定列中，并且我的页面上将出现类似“新记录已成功创建”的文本。但现在，出现了错误。

以下是我的php代码

<?php
$visitorname = $emailaddress = $visitorpassword = $confirmpassword = "";

$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "mydb";

if($_SERVER["REQUEST_METHOD"] == "POST"){
$visitorname = input($_POST["visitorname"]);
$emailaddress = input($_POST["emailaddress"]);
$visitorpassword = input($_POST["visitorpassword"]);
$confirmpassword = input($_POST["confirmpassword"]);
$hashed_password = password_hash($password, PASSWORD_DEFAULT);
}



function input($data){
    $data = trim($data);
    $data = stripslashes($data);
    $data = htmlspecialchars($data);
    return $data;
}
if($visitorpassword == $confirmpassword){


// Create connection
$conn = new mysqli($servername, $dbname);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
echo "Connected successfully";
$id = mysqli_insert_id($conn);
$sql = "INSERT INTO registereduser (id, username, emailaddress, 
hashedpassword) VALUES ($id, $visitorname, $emailaddress, 
$hashed_password)";

if ($conn->query($sql) === TRUE){

    echo "New record created successfully";
}else{
    echo "Errors " . $sql . "<br>" . $conn->error;
}
$conn->close();
}else{
    echo "Passwords do not match";
}
?>

以下是我的网页上显示的错误输出:

连接成功错误插入注册用户(id、用户名、电子邮件地址、散列密码)值(0、Josh5577、josh1998@hotmail.com、$2y$10$RMasEdVOskmcXbmfchLeBeUzLa5l38jXFaCQN7vMEhR8A0mU/iiC6)未选择数据库

Answer 1

请使用以下代码进行连接

$conn = new mysqli($servername, $username, $password, $dbname);