by Dinesh Thakur Category: Servlet with MySql Database

This Function Will Show the 'NULL value is equal or not'.

Then first i made a database named 'dbase' within the reference of mySql(php myAdmin). After i import all required java packages from java library. Then i made a class named ' MySqlNULLSAFEFunction', which extends 'HttpServlet'. After that i use service()Method that will bring the request from doGet()Method for output on the web browser. Then i loaded all the required drivers that are mandatory for database accessing. Then i use variable 'connection' that will use to create a link between the database and the java code. After i use 'resultSet' this variable will use to get the value from the columns and the rows. Then i use 'preparedStatement' that will use executing the selected Query like executeQuery as (SELECT NULL <=> 1, NULL <=> NULL, 7 <=> NULL).I use in the end doGet()Method that bring the output on the web browser.

Now i used some kind of 'HTML' code and tags that will present the output in a tabular form on a web browser.

import java.io.IOException;

import java.io.PrintWriter;
import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class MySqlNULLSAFEFunction extends HttpServlet
   {
       public void service(HttpServletRequest rq, HttpServletResponse rp)throws IOException, ServletException
         {
             rp.setContentType("text/html");
             PrintWriter disp = rp.getWriter();
             String driver = "com.mysql.jdbc.Driver";
             String url = "jdbc:mysql://localhost/dbase";
             String uid = "root";
             String psw = "root";
             Connection con=null;
             PreparedStatement ps = null;
             ResultSet rs;
             try
              {
                  Class.forName(driver);
                  con = DriverManager.getConnection(url,uid,psw);
                  ps=con.prepareStatement("SELECT NULL <=> 1, NULL <=> NULL, 7 <=> NULL");
                  rs = ps.executeQuery();
                              String title = "Using NULL SAFE EQUAL TO Function";
                  String docType ="<!doctype html public \"-//w3c//dtd html 4.0 " + "transitional//en\">\n";
                              disp.println(docType + "<html>\n" + "<head><title>" + title + "</title></head>\n" +
                  "<body bgcolor=\"#f4efef\">\n" + "<h1 align=\"center\">" + title + "</h1>\n" + "<ul>\n" +
                              "<table width=\"50%\" border=\"1\" align=\"center\">\n" + "<th>Value</th>\n"+ "</body> </html>");
                  while(rs.next())
                      {
                             String val = rs.getString(1);
                                         disp.println("<tr><td align=\"center\">" + val +"</td></tr>" );  
                      }      
               }          
                                         catch(Exception e) 
                                    {
                                         e.printStackTrace();
                                    }
                                         disp.close();
         }
                                         public void doPost(HttpServletRequest rq,HttpServletResponse rp)throws IOException,ServletException
                                                  {
                                                 doGet(rq,rp);
                                                  }
   }
WEB.xml
 
<servlet>
   <servlet-name>MySqlNULLSAFEFunction</servlet-name>
   <servlet-class>MySqlNULLSAFEFunction</servlet-class>
</servlet>
<!-- servlet mapping -->
<servlet-mapping>
   <servlet-name>MySqlNULLSAFEFunction</servlet-name>
   <url-pattern>/MySqlNULLSAFEFunction</url-pattern>
</servlet-mapping>




About Dinesh Thakur

Dinesh ThakurDinesh Thakur holds an B.SC (Computer Science), MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.



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