What potential pitfalls should be considered when using link parameters in PHP?

When using link parameters in PHP, it is important to be cautious of potential security vulnerabilities such as SQL injection attacks. To mitigate this risk, it is recommended to sanitize and validate any input received from link parameters before using them in database queries or other sensitive operations.

// Sanitize and validate link parameters before using them in database queries
$link_param = isset($_GET['param']) ? htmlspecialchars($_GET['param']) : '';

// Use the sanitized link parameter in a database query
$query = "SELECT * FROM table WHERE column = '" . $link_param . "'";