What are common pitfalls to avoid when integrating text fields and selection fields in PHP forms?

One common pitfall to avoid when integrating text fields and selection fields in PHP forms is not properly validating and sanitizing user input. This can lead to security vulnerabilities such as SQL injection attacks. To solve this issue, always validate and sanitize user input before processing it in your PHP code.

// Validate and sanitize user input for text field
$text_field = isset($_POST['text_field']) ? htmlspecialchars(trim($_POST['text_field'])) : '';

// Validate and sanitize user input for selection field
$selection_field = isset($_POST['selection_field']) ? htmlspecialchars(trim($_POST['selection_field'])) : '';