by Dinesh Thakur Category: Servlet with MySql Database

This function will show that the greater Number Between Two expressions.

Then i made a database named 'dbase' within the reference of mySql(php myAdmin). Here i call or import all the required java packages from java library. That after i made a class named 'MySqlGREATERFunction' extends 'HttpServlet'. I use here serviceMethod() that is responsible for the getting request from doGet()Method for output on the web browser. Here after i loaded all the required drivers for database accessing. Then after i need to be declare variables i use first 'connection' this variable is responsible for the creating a link between the database and the actual code. The second one i declare 'resultSet' this will use to get value from the selected columns and the rows as well. The next one i declare is to 'preparedStatement' this will be act as to executing the selected query like executeQuery() as (SELECT GREATEST(2,8)). In the last phase of coding i use doGet()Method that will be responsible for the output on web browser.

To getting output in tabular form i use some tags from 'HTML' that bring the result as desired on 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 MySqlGREATERFunction 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 GREATEST(2,8)");
                 rs = ps.executeQuery();
              String title = "Using GREATEST 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>MySqlGREATERFunction</servlet-name>
   <servlet-class>MySqlGREATERFunction</servlet-class>
</servlet>
<!-- servlet mapping -->
<servlet-mapping>
   <servlet-name>MySqlGREATERFunction</servlet-name>
   <url-pattern>/MySqlGREATERFunction</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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