i have placed four textbox inside the listview of web application. if i enter data in first textbox, its corresponding record should be fetched from oracle database and fetched record should be placed in 2,3,4 textbox.
If you're using webforms you could use a WebMethod to invoke the query from javascript, you can see an example here.
You could also just add a control that invokes a function server side and use the FindControl method of the ListView to obtain the value of your textbox. Also if you want the function/method to be called when the user stops typing you could use a jQuery plugin called typewatch you can find it here. Also taking into account the WebMethod* attribute that I mentioned earlier in the answer.
Go through the article Complete ListView in ASP.NET 3.5. This article shows how to place textboxes inside listview and edit the data in listview.
For Oracle connection in ASP.NET this article Connecting to an Oracle Database Using ASP.NET—A Step-by-Step Tutorial will definitly helps you