How can external form inputs be securely integrated with database queries in PHP to prevent unauthorized access or data leakage?

To securely integrate external form inputs with database queries in PHP, it is essential to use prepared statements with parameterized queries. This approach helps prevent SQL injection attacks by separating SQL logic from user input data. By binding parameters to placeholders in the query, the database engine can distinguish between the query structure and the user input, ensuring that potentially harmful input is treated as data rather than executable code. 

// Establish a database connection
$pdo = new PDO("mysql:host=localhost;dbname=mydatabase", "username", "password");

// Prepare a SQL statement with a parameterized query
$stmt = $pdo->prepare("SELECT * FROM users WHERE username = :username");

// Bind the user input to the parameter
$stmt->bindParam(':username', $_POST['username']);

// Execute the query
$stmt->execute();

// Fetch the results
$results = $stmt->fetchAll(PDO::FETCH_ASSOC);

// Process the results as needed
foreach ($results as $row) {
    // Handle the data
}

Keywords

SQL injection prepared statements PDO input validation data sanitization

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