无法连接到 MySQL，代码错误？

Question

我尝试连接到我的数据库，但没有任何效果...

这是我创建的代码：

$name ='testdb';
$user = 'root';
$password = '';
$host = 'localhost';

$link = new mysqli($name, $user, $password, $host);

$name = $_POST['name'];
$message = $_POST['message'];
$mail = $_POST ['mail'];

$name = $link->real_escape_string($_POST['name']);

$message = $link->real_escape_string($_POST['message']);

$mail = $link->real_escape_string($_POST['mail']);

$sql = "INSERT INTO test (Name, Message, Mail) VALUES ('$name','$message', '$mail')";

$result = $link->query($sql);

我已经仔细检查了所有的拼写。谁能给我一些提示？我可能瞎了。

Answer 1

您似乎没有正确初始化 mysqli 连接

error_reporting(E_ALL);//display all errors   

$name ='testdb';
$user = 'root';
$password = '';
$host = 'localhost';

$link = new mysqli($host, $user, $password, $name);

Use prepared statements(Prevents SQL injection)

$sql = "INSERT INTO test (Name, Message, Mail) VALUES (?,?,?)";//placeholders (3placeholders for 3values)
$statement = $link->prepare($sql);//prepare query. returns true/false
$statement->bind_param('sss',$name, $message, $mail);//you dont need to escape anymore
$statement->execute(); //execute safely

Answer 2

mysqli 的第一个参数是主机名，你交换了 hostname 和 databasename Connect to MySQL

$link = new mysqli($host, $user, $password, $name);

你也可以使用prepared statement，来防止SQL injections

A prepared statement is a feature used to execute the same (or similar) SQL statements repeatedly with high efficiency.

$sql = "INSERT INTO test (Name, Message, Mail) VALUES (?,? ?)";
$stmt =  $link->prepare($sql);
$stmt->bind_param("sss",$name, $message, $mail);
$result = $stmt->execute();
if ($result) {
    // query was successful
}else {
    // query failure
}

Answer 3

请使用下面的代码，它会对您有所帮助

$name ='testdb';
$user = 'root';
$password = '';
$host = 'localhost';

$link = new mysqli($host,$user,$password,$name);
// Check connection
if ($link->connect_error) {
    die("Connection failed: " . $link->connect_error);
} 
$name = $_POST['name'];
$message = $_POST['message'];
$mail = $_POST ['mail'];

$name = $link->real_escape_string($_POST['name']);

$message = $link->real_escape_string($_POST['message']);

$mail = $link->real_escape_string($_POST['mail']);

$sql = "INSERT INTO test (Name, Message, Mail) VALUES ('$name','$message', '$mail')";



if ($link->query($sql) === TRUE) {
    echo "New record created successfully";
} else {
    echo "Error: " . $sql . "<br>" . $link->error;
}

$link->close();

要学习 PHP 和 MYSQL 中的基本内容，请参阅此 link https://www.w3schools.com/php/

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