Updating the Database
This is handled by a servlet that normally generates no output. When it is finished it just redirects the browser back to the selection page.
The session handling is slightly different to Select. In this case if the servlet cannot find a current session it will report an error.
The servlet extracts the row associated with the selected login ID.
For future reference, it saves the current value of the fields in the session object.
It generates the HTML for the displayed page.