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Retrieving Data from the table using Statement

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In this program we are going to fetch the data from the database in the table from our java program.

Retrieving Data from the table using Statement

     

In this program we are going to fetch the data from the database in the table from our java program.  

To accomplish our goal we first have to make a class named as ServletFetchingData which must extends the abstract HttpServlet class, the name of the class should be such that the other person can understand what this program is going to perform. The logic of the program will be written inside the doGet() method which takes two arguments, first is HttpServletRequest interface and the second one is the HttpServletResponse interface and this method can throw ServletException.

Inside this method call the getWriter() method of the PrintWriter class. We can retrieve the data from the database only and only if there is a connectivity between our database and the java program. To establish the connection between our database and the java program we firstly need to call the method forName() which is static in nature of the class ClassLoader. It takes one argument which tells about the database driver  we are going to use. Now use the static method getConnection() of the DriverManager class. This method takes three arguments and returns the Connection object. SQL statements are executed and  results are returned within the context of a connection. Now your connection has been established. Now use the method createStatement() of the Connection object which will return the Statement object. This object is used for executing a static SQL statement and obtaining the results produced by it. As we need to retrieve the data from the table so we need to write a query to select all the records from the table. This query will be passed in the executeQuery() method of Statement object, which returns the ResultSet object. Now the data will be retrieved by using the getString() method of the ResultSet object.

The code of the program is given below:

import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class ServletFetchingDataFromDatabase1 extends HttpServlet{
  public void doGet(HttpServletRequest request, HttpServletResponse 
  response
)throws ServletException, IOException{
  response.setContentType("text/html");
  PrintWriter pw = response.getWriter();
  String connectionURL = "jdbc:mysql://localhost/zulfiqar";
  Connection connection=null;
  try{
  Class.forName("org.gjt.mm.mysql.Driver");
  connection = DriverManager.getConnection(connectionURL, "root",
    
"admin");
  Statement st = connection.createStatement();
  ResultSet rs = st.executeQuery("Select * from emp_sal");
  while(rs.next()){
  pw.println("EmpName" " " "EmpSalary" "<br>");
  pw.println(rs.getString(1" " + rs.getString(2"<br>");
  }
  }
  catch (Exception e){
  pw.println(e);
  }
  }
}

XML File for this program:

<?xml version="1.0" encoding="ISO-8859-1"?>
<!--<!DOCTYPE web-app
 PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd"> -->

<web-app>
 <servlet>
  <servlet-name>Hello</servlet-name>
  <servlet-class>ServletFetchingDataFromDatabase</servlet-class>
 </servlet>
 <servlet-mapping>
 <servlet-name>Hello</servlet-name>
 <url-pattern>/ServletFetchingDataFromDatabase</url-pattern>
 </servlet-mapping>
</web-app>

The output of the program is given below: 

Table in the database:

mysql> select * from emp_sal;
+----------+--------+
| EmpName | salary |
+----------+--------+
| zulfiqar | 15000 |
| vinod | 12000 |
+----------+--------+
2 rows in set (0.00 sec)

Download this example:

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Posted on: July 17, 2007

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