What are the best practices for handling form data in PHP to ensure accurate query filtering?

When handling form data in PHP to ensure accurate query filtering, it is important to sanitize and validate user input to prevent SQL injection attacks and ensure data integrity. One way to achieve this is by using prepared statements with parameterized queries to securely interact with the database. Additionally, implementing input validation functions and filtering mechanisms can help to ensure that only valid and expected data is processed. 

// Sample PHP code snippet for handling form data with prepared statements

// Assuming form data is submitted via POST method
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // Establish database connection
    $conn = new mysqli("localhost", "username", "password", "database");

    // Check connection
    if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);
    }

    // Prepare SQL statement with placeholders
    $stmt = $conn->prepare("SELECT * FROM users WHERE username = ? AND email = ?");

    // Bind parameters to placeholders
    $stmt->bind_param("ss", $username, $email);

    // Sanitize and validate form data
    $username = filter_var($_POST["username"], FILTER_SANITIZE_STRING);
    $email = filter_var($_POST["email"], FILTER_SANITIZE_EMAIL);

    // Execute the prepared statement
    $stmt->execute();

    // Process the query result
    $result = $stmt->get_result();

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

Keywords

form data PHP query filtering validation security

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