In-depth analysis of the core points of PHP backend design

As a popular back-end programming language, PHP plays a very important role in web development. In PHP backend design, there are some core points that require in-depth analysis, so as to help us better implement an efficient and safe backend system. Let's take a closer look at these core points and corresponding code examples.

1. Database connection

In PHP background design, connecting to the database is a very important link. We need to use the correct code to connect to the database and ensure that the connection is safe and reliable. The following is a code example for connecting to a MySQL database:

$servername = "localhost"; //数据库服务器名称
$username = "username"; //连接数据库的用户名
$password = "password"; //连接数据库的密码
$dbname = "myDB"; //要连接的数据库名称

// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 检测连接是否成功
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

In the above code, we use the mysqli class to create a connection and determine whether the connection is successful through the connect_error attribute. If the connection fails, we print the error message through the die() function and end the script execution.

2. SQL injection protection

SQL injection is a very common attack method that can obtain database information or execute specified SQL statements under illegal circumstances. In order to prevent SQL injection attacks, we need to process and filter user-entered data to ensure security. The following is a code example to prevent SQL injection:

$uname = $conn->real_escape_string($_POST['username']);
$upass = $conn->real_escape_string($_POST['password']);

$sql = "SELECT * FROM users WHERE username = '".$uname."' AND password = '".$upass."'";

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

if ($result->num_rows > 0) {
    //登录成功
} else {
    //登录失败
}

In the above code, we use the real_escape_string() method on the mysqli object to filter the entered user name and password to prevent SQL injection attacks.

3. Data Storage

In PHP background design, we usually need to store data submitted by users. When storing data, we need to use correct methods to handle different types of data to ensure the integrity and accuracy of data storage. The following is a code example for inserting user data into a MySQL database:

$uname = $conn->real_escape_string($_POST['username']);
$upass = $conn->real_escape_string($_POST['password']);
$uemail = $conn->real_escape_string($_POST['email']);

$sql = "INSERT INTO users (username, password, email) VALUES ('".$uname."', '".$upass."', '".$uemail."')";

if ($conn->query($sql) === TRUE) {
    //插入成功
} else {
    //插入失败
}

In the above code, we use the INSERT INTO keyword to insert user data into the users table, and use the VALUES clause to set the corresponding field value. Execute the SQL statement through the query() method, and use $== TRUE to detect whether the insertion is successful.

4. File upload

In PHP background design, we usually need to implement the file upload function for users to submit and process files. When uploading files, we also need to use correct methods to process and filter data to ensure the security and reliability of file uploads. The following is a code example for file upload:

$target_dir = "uploads/";
$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
$uploadOk = 1;
$imageFileType = strtolower(pathinfo($target_file,PATHINFO_EXTENSION));

// 检测文件是否为图像
if(isset($_POST["submit"])) {
    $check = getimagesize($_FILES["fileToUpload"]["tmp_name"]);
    if($check !== false) {
        // 是图像
        $uploadOk = 1;
    } else {
        // 不是图像
        $uploadOk = 0;
    }
}

// 检测文件是否已经存在
if (file_exists($target_file)) {
    $uploadOk = 0;
}

// 尝试上传文件
if ($uploadOk == 0) {
    // 上传失败
} else {
    if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) {
        //上传成功
    } else {
        // 上传失败
    }
}

In the above code, we use the $_FILES global variable to obtain the information of the uploaded file, and use the $pathinfo() function to obtain the file suffix. At the same time, we use the move_uploaded_file() function to move the file to the specified upload directory, and detect whether the upload is successful through error handling.

To sum up, the core points of PHP backend design include database connection, SQL injection protection, data storage and file upload. Using the correct code to implement these points can help us develop efficient and secure backend systems.

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