In PHP, what are the advantages and disadvantages of storing phone numbers as VARCHAR in a database, considering different input formats and user preferences?

Storing phone numbers as VARCHAR in a database allows for flexibility in accommodating different input formats and user preferences. However, it can lead to inconsistencies in data entry and querying if not properly validated and formatted. To address this, it is recommended to implement input validation and normalization functions to ensure consistent storage and retrieval of phone numbers.

// Input validation and normalization function for storing phone numbers as VARCHAR in a database

function validatePhoneNumber($phoneNumber) {
    // Remove all non-numeric characters
    $phoneNumber = preg_replace('/\D/', '', $phoneNumber);
    
    // Add country code if missing
    if(strlen($phoneNumber) == 10) {
        $phoneNumber = '1' . $phoneNumber;
    }
    
    return $phoneNumber;
}

// Example usage
$userPhoneNumber = validatePhoneNumber($_POST['phone_number']);
// Store $userPhoneNumber in the database