Inserting Record In Database Using Servlet

Inserting Record In Database Using Servlet.java

package studentMain;

import java.io.IOException; 
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; 
import net.sf.json.JSONObject;
import org.json.JSONArray;
import java.sql.Connection;
import java.sql.ResultSet; 
import java.sql.PreparedStatement;

public class GapSpecificationDetailsUpdate extends HttpServlet 
{
	private static final long serialVersionUID = 1L;
	Connection conn;
	ResultSet rs;
	PreparedStatement ps;
       
    public GapSpecificationDetailsUpdate() 
    {
        super();
        conn = ConnectionClassForMyProjectWindow.getConnection();
    } 
    
    public void process(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException
    {
    	try
    	{
    		String nameId = request.getSession().getAttribute("userid").toString();
    		String FromYear = request.getParameter("txtFromYear");
    		String ToYear = request.getParameter("txtToYear");
    		String Reason = request.getParameter("txtReason");
    		String switchFlag = request.getParameter("txtCheckFlag");
    	
       	 	String selectQuery=" select sgd.student_Id,sgd.from_year,sgd.to_year,sgd.gap_description "+
       	 					   " from student_gap_description sgd "+
       	 					   " where sgd.student_Id='"+nameId+"'";
    		
    		String insertQuery = " insert into student_gap_description values(?,?,?,?) ";

    	
    		ps = conn.prepareStatement(selectQuery);
    		rs=ps.executeQuery();
    		PrintWriter out=response.getWriter();
    		
    		rs.last();
    		int size=rs.getRow();
    		rs.beforeFirst();
    		
    		if(switchFlag.compareTo("1")==0)
    		{
 	    		JSONArray jArray = new JSONArray ();  	    		
 	    		jArray.put(size); 	
 		    	while(rs.next()) 
 		    	{ 	 	    			    		
 		    		JSONObject jObj = new JSONObject(); 
 		 					
 					jObj.put("from_year",rs.getString("from_year"));
 					jObj.put("to_year",rs.getString("to_year")); 
 					jObj.put("gap_description",rs.getString("gap_description")); 
 					
 					jArray.put(jObj);  							 
 		    	} 
 		    	out.print(jArray);		    	
    		} 
    		else
    		{
		 		ps = conn.prepareStatement(insertQuery);
		 		ps.setString(1, nameId);
				ps.setString(2, FromYear);
				ps.setString(3, ToYear);
				ps.setString(4, Reason);
				
				int cnt = ps.executeUpdate();
				System.out.println(cnt);
								
				out.print(cnt);	    		
    		}
    	}
    	catch(Exception e)
    	{
    		System.out.println(e);
    	}
    }
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
	{
		this.process(request, response);
	}
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
	{
		this.process(request, response);
	}
}