I'm a beginner... I have a simple web application using JSP, Tomcat and MYSQL. My Application is like simple form that input student name to insert into database. then i post the data to one servlet.. that will do the inserting... after insert my servlet will query all student name from database and set attribute as an object. Then, using Request Dispatcher i forward to a jsp page that will display all the student name by querying the object that been set in the servlet. The problem is.. when i refresh the display all student name page, it will redo the inserting process making the student name to be duplicate.. how do i avoid this kind of thing ?