MySql HOUR() Function Example using Java Servlet

In this section you will learn how to use MySql hour() function in Java Servlet.

MySql HOUR() Function Example using Java Servlet

In this section you will learn how to use MySql hour() function in Java Servlet.

HOUR() function of MySql returns an hour part from the time or datetime. It may returns the value range between 0 - 23, it may also be greater than 23.

Syntax :

HOUR(time/datetime)

Here the argument time is hh-mm-ss or datetime is yyyy-mm-dd hh-mm-ss.

Now, since I have to use this function in java servlet program, therefore I have created a java servlet class named MysqlHourServlet which extends the HttpServlet class. In the body of class I overridden the method doGet() and created an objects of HttpServletRequest and HttpServletResponse into its parameter. Inside the doGet() method first I set the mime type that in which format the browser will show the output. In the next line I used the getWriter() method of ServletResponse interface with the object of HttpServletResponse. HttpServletResponse interface extends this method from the ServletResponse. In continue we have to make a connection between java code and database system. So, since I am using Mysql in the example given below therefore, I am loading the driver of mysql and make a connection by using the getConnection() method of DriverManager class. It returns a Connection. Further I am passing the query "SELECT now() as curr_time, HOUR(now()) as hh;" (This query will return the output as  2011-08-10 04:38:30   5) into the parameter of prepareStatement() method of Connection interface which gives an object of PreparedStatement interface. In the next line I used the executeQuery() method of PreparedStatement interface which returns a ResultSet object that holds the result of query. At last I have extracted the result from the ResultSet object.

Example :

MysqlHourServlet.java

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;
import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class MysqlHourServlet extends HttpServlet
{
 public void doGet(HttpServletRequest req, HttpServletResponse res)
  throws IOException, ServletException
  {
   res.setContentType("text/html");
   PrintWriter pw = res.getWriter();
   String className = "com.mysql.jdbc.Driver";
   String url = "jdbc:mysql://192.168.10.13/data";
   String user = "root";
   String password = "root";
   String sql = "SELECT now() as curr_time, HOUR(now()) as hh;";
   Connection con;
   PreparedStatement ps;
   ResultSet rs;
   
   try
   {
	Class.forName(className);
	con = DriverManager.getConnection(url, user, password);
	ps = con.prepareStatement(sql);
	rs = ps.executeQuery();
	
	pw.println("<table>");
	pw.println("<tr>");
	pw.println("<td><b>curr_time</b></td>");
	pw.println("<td><b>hh</b></td>");
	pw.println("</tr>");
	while(rs.next())
	{
		String hour = rs.getString(1);
		String hh = rs.getString(2);
		pw.println("<tr>");
		pw.println("<td>"+hour+"</td>");
		pw.println("<td>&nbsp;"+hh+"</td>");
		pw.println("</tr>");
	}
	pw.println("</table>");
	}
    catch(SQLException sx)
    {
      pw.println(sx);
    }
    catch(ClassNotFoundException cx)
    {
      pw.println(cx);
    }
  }
}

web.xml

<?xml version="1.0" encoding="UTF-8"?>

<web-app id="WebApp_ID" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

<display-name>mysqlDate</display-name>



<servlet>

<servlet-name>MysqlHourServlet</servlet-name>

<servlet-class>MysqlHourServlet</servlet-class>

</servlet>



<servlet-mapping>

<servlet-name>MysqlHourServlet</servlet-name>

<url-pattern>/MysqlHourServlet</url-pattern>

</servlet-mapping>



</web-app>

Output :

Download Source Code