add special characters to DB?

Hello,

I have a question about preg_match, I couldn’t understand how it works. Code below allow me to add word without space and special characters. I want to add words for another language, which contains spaces and special character like (â, ế, đ…) but not (?, #, %...etc). So my questions are:

1. I set DB to utf8_general_ci, is it correct? To show special unicode characters

2. How to modifly code below to make it adds words with space and special unicode characters? I think it is about preg_match, but I don’t know how it works ???

function add_new_word($word){
	if (preg_match('/^[a-zA-Z]+$/', $_POST['word'])) {
		$word = $_POST['word'];
	} else {
		echo 'Illegal parameters!';
		exit();
	}

	if (add_word($word)) {
		echo "<p>Successfully added word! </p>";
	} else {
		echo "<p>Failure! Unable to add word! </p>";
	}
	echo "<b>Word:</b> $word<br/>";
}

PHP:

Thank you