Duplicate entry in registration form!!!

[anki1234]

Hi All,
I have a application in struts framework which requires username password for login.If NewUser then I have a registration form to be filled by the user to register. The problem is that I am unable to stop duplicate values in the username field.I can do tat by making username as primary key in database but tat will not provide error information to user except providing error at server side.Can anybody tell me t way to do this.
Thank u All
ankit

[wsaryada]

Why don't you just check whether the username has already been taken by other user? You can just query your user table for the username, if it already use then tell her or him to use another username.