What are the potential pitfalls of importing values from external files in PHP prepared statements?

Potential pitfalls of importing values from external files in PHP prepared statements include the risk of exposing sensitive information if the external file is not properly secured, the possibility of injecting malicious code if the input is not sanitized, and the potential for errors if the file path or content is not correctly handled. To mitigate these risks, it is important to validate and sanitize the imported values before using them in prepared statements. Additionally, restricting access to the external file and ensuring that it is stored securely can help prevent unauthorized access.

// Example of importing values from an external file securely
$file = 'values.txt';

if (file_exists($file)) {
    $value = file_get_contents($file);
    
    // Sanitize the imported value
    $value = filter_var($value, FILTER_SANITIZE_STRING);
    
    // Prepare and execute the SQL statement with the sanitized value
    $stmt = $pdo->prepare("INSERT INTO table_name (column_name) VALUES (?)");
    $stmt->execute([$value]);
} else {
    echo "File not found.";
}