by Dinesh Thakur Category: Servlet with MySql Database

The Function 'CONCAT' will add Two String with each other.

In the first instance i make a table  with required Fields and values into the database named 'dbase' within the reference of mySql(php myAdmin).then i import all the required java packages from java library. Then i make a class named 'MySqlConcatFunc' which extends the 'HttpServlet'. I use serviceMethod() which will bring the request from doGet()Method for output on the web browser. After that i loaded all the required drivers for database accessing. Here i declare some mandatory variables like i declare Connection (this variable will create a link between database and the java code). Then i use 'resultset' that will bring the value from the required columns and rows. i declare 'preparedStatement' that will responsible for the executing selected query like executeQuery() as (Select CONCAT('My','S','ql'). Then i use doGet()Method for getting output on the web Browser.

To Getting Output on web browser in a tabular form i use 'HTML' code and tags.

EXAMLPE

 
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 MySqlConcatFunc 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 CONCAT('My','S','ql')");
          rs = ps.executeQuery();
              String title = "Using Concat 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 Is </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>MySqlConcatFunc</servlet-name>
   <servlet-class>MySqlConcatFunc</servlet-class>
</servlet>
<!-- servlet mapping -->
<servlet-mapping>
   <servlet-name>MySqlConcatFunc</servlet-name>
   <url-pattern>/MySqlConcatFunc</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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