How can PHP developers prevent SQL injection vulnerabilities when working with user authentication in a web application?

SQL injection vulnerabilities can be prevented in PHP by using prepared statements with parameterized queries when interacting with the database. This approach ensures that user input is treated as data rather than executable SQL code, thus preventing malicious SQL injection attacks. 

// Example code snippet using prepared statements to prevent SQL injection
$username = $_POST['username'];
$password = $_POST['password'];

$stmt = $pdo->prepare("SELECT * FROM users WHERE username = :username AND password = :password");
$stmt->bindParam(':username', $username);
$stmt->bindParam(':password', $password);
$stmt->execute();

// Check if the user exists and the password is correct
$user = $stmt->fetch();
if ($user) {
    // User authentication successful
} else {
    // User authentication failed
}

Keywords

SQL injection PHP user authentication prepared statements security

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