if there is no field in data base for storing the last login information(System date and time) then how can we able to know the last login information in a web-based application(servlet/jsp/struts)
You could add a field to your database. If the amount of data you need to store is both small and not sensitive in nature, you could store it in a cookie as well. Of course, if you use a cookie, this information will only be seen if the user logs in from the same machine next time.