How to call a function after textbox lose focus

Question

I have no experience with Javascript/JQuery/AJAX so I'm trying to understand if it's possible to call a function that execute a query on my DB after a textbox lose focus.

I'm displaying a table in my page (using PHP) with text boxes that contains the same values of a table on my DB, and when someone change the value on a text box I want to change the DB table with an UPDATE query to make them equals; is that a way with AJAX or JQuery to do this?

Answer 1

<input type="text" id="check">​

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>

<script type="text/javascript">
$("#check").blur(function() {
 alert('working');
});​
</script>