What potential pitfalls should be considered when handling form data and database queries in PHP?

One potential pitfall when handling form data and database queries in PHP is the risk of SQL injection attacks if user input is not properly sanitized. To prevent this, always use prepared statements with parameterized queries to securely interact with the database. Additionally, validate and sanitize user input before using it in SQL queries to avoid any malicious code execution. 

// Example of using prepared statements to handle form data and database queries securely

// Assuming $conn is the database connection object

// Sanitize user input
$username = filter_var($_POST['username'], FILTER_SANITIZE_STRING);
$password = filter_var($_POST['password'], FILTER_SANITIZE_STRING);

// Prepare the SQL query using a prepared statement
$stmt = $conn->prepare("SELECT * FROM users WHERE username = ? AND password = ?");
$stmt->bind_param("ss", $username, $password);

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

// Process the results as needed
$result = $stmt->get_result();
while ($row = $result->fetch_assoc()) {
    // Handle the retrieved data
}

// Close the statement and connection
$stmt->close();
$conn->close();

Keywords

SQL injection data validation prepared statements cross-site scripting PDO.

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