count(*) 是返回记录集条数的吧?????????
我不太明白你问的意思,类似注册时不能有相同用户名的应用么?
如果是的话就加个判断呗,
先 ResultSet rs = select *** from [table] where [filter]
然后 if(rs!=null & !(rs.next().equals(request.getParameter(name))))
        [do what you want];
     else
        [error alert:something that the customer applies has been applied by others !!];
看的懂么?