What best practices should be followed when handling user input and database interactions in PHP to prevent errors like missing form elements?

When handling user input and database interactions in PHP, it is crucial to validate all incoming data and ensure that all required form elements are present before processing the data. One way to prevent errors like missing form elements is to use conditional statements to check if the required fields are set before proceeding with the database interaction. 

// Validate and process user input
if(isset($_POST['username']) && isset($_POST['password'])) {
    $username = $_POST['username'];
    $password = $_POST['password'];
    
    // Database interaction
    $conn = new mysqli($servername, $dbusername, $dbpassword, $dbname);
    
    $sql = "INSERT INTO users (username, password) VALUES ('$username', '$password')";
    
    if($conn->query($sql) === TRUE) {
        echo "New record created successfully";
    } else {
        echo "Error: " . $sql . "<br>" . $conn->error;
    }
    
    $conn->close();
} else {
    echo "Username and password are required fields";
}

Keywords

SQL injection prepared statements data validation error handling input sanitization

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