Please solve my error occured java.lang.NullPointerExceptio

This is my code: I figured out the else part of the code causing this error. But i don't understand what is that. Can anyone solve this. Any kind of help suggestion will be appreciated. Thanks

Code :

---

<%@ page import="INCLUDES.DBConnection"%>
<%@ page import="java.sql.*"%>
<%@ page import="java.io.*"%>
<jsp:useBean id="DB" scope="page" class="INCLUDES.DBConnection"/>
<jsp:setProperty name="DB" property="*"/>
<%
	String user_name=request.getParameter("user_name");
	ResultSet objRs=null;
	String statement="";
	try
	{
		statement="select * from x_master_elearning_user where user_name='" +
 user_name + "'";
		DB.setStatement(statement);
		objRs=(ResultSet)DB.resultUpdate();
 
		if(objRs.next())
		{
			response.sendRedirect("signup.jsp");
		}
		else
		{
			objRs.updateString("user_name",user_name);
			objRs.updateString("pass_word",request.getParameter("pass_word"));
			objRs.updateString("first_name",request.getParameter("trainee_name"));
			objRs.updateString("designation",request.getParameter("designation"));
			objRs.updateString("email",request.getParameter("email"));
			objRs.updateString("city",request.getParameter("city"));
			objRs.updateString("country",request.getParameter("country"));
			objRs.insertRow();
			response.sendRedirect("course_list_index2.jsp");
		}
 
	}
	catch(Exception e)
	{	
	        out.print("error occured " + e);
	}
%>

---

Hello there,

First of all could you tell us where you are getting the nullpointer? It could be because there is no resultset so objRs.next will throw a nullpointerexception.

On another note I see that you're grabbing the username off the request parameters and passing it into your SQL query, this is a MAJOR security hole and you are effectively giving anyone access to everything in your database.

See SQL injection - Wikipedia, the free encyclopedia

You should be using PreparedStatement instead and not concatenate your SQL query with user input variables.

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