关于jsp修改Oracle数据库中记录的问题

代码大致如下：
public boolean update(Provider p){
boolean isUpdate=false;
openConection();
String sql="update provider set p_id=?,providername=?,description=?,contacts=?,telephone=?,fax=?,address=?";
try {
ps=con.prepareStatement(sql);
ps.setInt(1,p.getPid());
ps.setString(2,p.getProvidername());
ps.setString(3,p.getDescription());
ps.setString(4,p.getContacts());
ps.setString(5,p.getTelephone());
ps.setString(6,p.getFax());
ps.setString(7,p.getAddress());
int count=ps.executeUpdate();
isUpdate=count>0?true:false;
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
shutdown();
}
return isUpdate;
}

<%
Provider p2=new Provider();
String msg=request.getParameter("msg");
if("update".equals(msg)){
String name2=request.getParameter("proName");
p2.setProvidername(name2);
String desc2=request.getParameter("proDesc");
p2.setDescription(desc2);
String contact2=request.getParameter("contact");
p2.setContacts(contact2);
String phone2=request.getParameter("phone");
p2.setTelephone(phone2);
String fax2=request.getParameter("fax");
p2.setFax(fax2);
String address2=request.getParameter("address");
p2.setAddress(address2);
boolean isUpdate=digger.update(p2);
if(isUpdate){
out.println("<script type=\"text/javascript\">");
out.print("alert(\"添加成功\")");
out.println("</script>");
}else if(!isUpdate){
out.println("<script type=\"text/javascript\">");
out.print("alert(\"添加失败\")");}
out.println("</script>");
}

%>
<input name="button" id="button" value="修改" class="input-button" type="submit" onclick="location.href='providermodify.jsp?msg=update'">
执行后数据库中内容被清空！！！！！
求解！！！