LostFocus on text box event in asp
<p>Hi I am currently developing a web app in ASP.net. I am creating a registration form where when the user enter a username they would like to use it performs a check on the database to see if the username already exists. I don't want this to be done in the text changed event because I don't want it to try and query the database each time a character is entered into the text box. When I want to do is when that text boxes loses focus, either by tapping to the next field or clicking on another field it then checks the database for the username. If the username already exits then a message like a tooltip is placed to the side of the field. </p>

<p>How can I perform this action when the text box loses focus. </p>
