PHP Database Connection Security: Ways to Prevent SQL Injection Attacks

PHP Database Connection Security: Methods to Prevent SQL Injection Attacks

Introduction:
In the process of developing web applications, the database is a very important component one. However, incorrect or insecure database connections may allow malicious users to conduct SQL injection attacks, which will seriously threaten the security of our applications. In order to protect the application from SQL injection attacks, we need to take some security measures. This article will introduce some commonly used PHP database connection security methods and give corresponding code examples.

1. Use prepared statements (Prepared Statements)
A prepared statement is a SQL statement template that can be executed multiple times. By separating user data from query logic, prepared statements can effectively prevent SQL injection attacks. The following is an example of using prepared statements:

// 数据库连接参数
$servername = "localhost";
$username = "root";
$password = "password";
$dbname = "mydb";

// 创建数据库连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接是否成功
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 使用预处理语句进行查询
$stmt = $conn->prepare("SELECT * FROM users WHERE username = ? AND password = ?");
$stmt->bind_param("ss", $username, $password);

// 设置查询参数
$username = $_POST['username'];
$password = $_POST['password'];

// 执行查询
$stmt->execute();

// 处理查询结果
$result = $stmt->get_result();
while ($row = $result->fetch_assoc()) {
    // 处理每一行的数据
}

// 关闭连接
$stmt->close();
$conn->close();

2. Using parameterized queries
Parameterized query is a technology that passes the value of user data as a parameter to an SQL query. By using parameterized queries, we can effectively prevent SQL injection attacks. The following is an example of using parameterized queries:

// 数据库连接参数
$servername = "localhost";
$username = "root";
$password = "password";
$dbname = "mydb";

// 创建数据库连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接是否成功
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 准备查询语句
$stmt = $conn->prepare("SELECT * FROM users WHERE username = ? AND password = ?");

// 绑定查询参数
$stmt->bind_param("ss", $_POST['username'], $_POST['password']);

// 执行查询
$stmt->execute();

// 处理查询结果
$result = $stmt->get_result();
while ($row = $result->fetch_assoc()) {
    // 处理每一行的数据
}

// 关闭连接
$stmt->close();
$conn->close();

3. Use filter functions
PHP provides some filter functions, such as mysqli_real_escape_string, which can be used to convert input strings Definition to prevent SQL injection attacks. The following is an example of using the mysqli_real_escape_string function:

// 数据库连接参数
$servername = "localhost";
$username = "root";
$password = "password";
$dbname = "mydb";

// 创建数据库连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接是否成功
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 过滤输入的字符串
$username = mysqli_real_escape_string($conn, $_POST['username']);
$password = mysqli_real_escape_string($conn, $_POST['password']);

// 执行查询
$sql = "SELECT * FROM users WHERE username = '$username' AND password = '$password'";
$result = $conn->query($sql);

// 处理查询结果
if ($result->num_rows > 0) {
    while ($row = $result->fetch_assoc()) {
        // 处理每一行的数据
    }
} else {
    echo "0 结果";
}

// 关闭连接
$conn->close();

Conclusion:
Database connection security is an issue that must be taken seriously when developing Web applications. By using methods such as prepared statements, parameterized queries, and filter functions, we can effectively prevent SQL injection attacks. In actual development, we should choose the appropriate method according to the specific situation and follow best practices to protect the security of our applications.

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