I need to validate free flow textbox value matches value from database table
<p>I need to validate a given Name field in the asp.net form.</p>

<p>User Name: Alex Brandon</p>

<p>In the database, we have a users table with user_name column.</p>

<p>I need to validate on lost focus of User Name form field, that it exists in the users table and is valid else show an alert.</p>

<p>Does somebody has a ready solution to this?</p>
