I have a web site. The user input is a record id. When the form is submitted, the cgi code will check if the id is in the data base, if it’s in the database, it will be processed, and results being displayed. If the id is not in the database, I need to pop up a window telling the user the next available id, and when the user closes the popup window, the browser should go back to the first form submit page, with the next available id in the input box.

Right now, I can pop up an alert window telling the next available id, but have no idea how to go back to the submit page when I close the alert window.

Could anyone give me some suggestions?
Thanks!!

You cannot "popup" a window from server side code.

When the page returns the server script will need to write the new id into the form and trigger an alert box to inform the user.

You can use target, either in the form tag or via javascript, but it's an ugly thing to do (and often disallowed by browsers). Just handle it all in the "main" window.