by Dinesh Thakur Category: Servlet with MySql Database

This function 'CONCAT_WS' returns the value with separater.

i make a table in a database named 'dbase' with mandatory fields and value in it within the reference of mySql(php myAdmin). Then i import all the required java packages from java library. I made a class named 'MySqlConcatSeparatorFunc' which completely extends the 'HttpServlet'.i used serviceMethod() which is responsible for getting request from doGet()Method for output on the web browser. Before declaring the variables i loaded all the required drivers for database accessing. Then i declare some mandatory variable like i declare 'Connection' which is been responsible for creating a link between database and the java code. The other variable will be 'resultSet' this variable will use to get the value from selected columns and rows on the output table. The other variable is 'preparedStatement' this variable is used to executing the selected query like executeQuery() as (Select CONCAT_WS(',','Radhika','Tanwar')). In last i use doGet() method which will bring the output as required condition.

as on the web browser to get output in a manner way i use some tags of 'HTML' which appear the output in a tabular form.


 

EXAMPLE
 
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 MySqlConcatSeparatorFunc 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_WS(',','Radhika','Tanwar')");
         rs = ps.executeQuery();
             String title = "Using Concat With Separator 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>MySqlConcatSeparatorFunc</servlet-name>
   <servlet-class>MySqlConcatSeparatorFunc</servlet-class>
</servlet>
<!-- servlet mapping -->
<servlet-mapping>
   <servlet-name>MySqlConcatSeparatorFunc</servlet-name>
   <url-pattern>/MySqlConcatSeparatorFunc</url-pattern>
</servlet-mapping>




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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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