In this tutorial you will learn about how to use pi() function in math function of mysql using servlet.
MySql PI() Function Example Using Java Servlet
In this tutorial you will learn about how to use pi() function in math function of mysql using servlet.
PI() function in MySql gives the value of constant PI i.e 3.141593_ _ _ . In mathematics PI is also denoted by π, it is a constant of ratio of the (circumference of a circle) / (diameter of that circle). Generally 3.14 is used as the approximate value of π. Using this function you can perform the mathematical operations such as addition, subtraction, multiplication, division etc.
Syntax :
pi();
In this example I am doing the multiply operation.
Now, since I have to use this function in java servlet program, therefore I have created a java servlet class named MysqlPiServlet 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 Next step I am taking inputs using the getParameter() method of ServletRequest with the object of HttpServletRequest. In continue we have to establish 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 passed the query "SELECT PI()*"+n; (Here 'n' is a variable that stores the value given by the user in their respective textfields.) for the numeric value to do multiplication and "SELECT PI()"; for the empty value 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 :
pi.html
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>PI() Function</title> </head> <body> <form method="get" action="MysqlPiServlet"> <table> <tr> <td>NOTE : If you will not entered the value it will simply return the value of PI</td> </tr> <tr> <td>Enter a value<input type="text" name="text1"/></td> </tr> <tr> <td align="center"> <input type="submit" value ="ok"/></td> </tr> </table> </form> </body> </html>
MysqlPiServlet.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 MysqlPiServlet extends HttpServlet
{
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException
{
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String className = "com.mysql.jdbc.Driver";
String url = "jdbc:mysql://192.168.10.13";
String user = "root";
String password = "root";
String num = request.getParameter("text1");
Connection con;
PreparedStatement ps;
ResultSet rs;
try
{
Class.forName(className);
con = DriverManager.getConnection(url, user, password);
if(num =="")
{
String sql = "SELECT PI()";
ps = con.prepareStatement(sql);
rs = ps.executeQuery();
while(rs.next())
{
String pi = rs.getString(1);
out.println("<html>");
out.println("pi = "+pi);
out.println("</html>");
}
}
else
{
double n = Double.parseDouble(num);
String sql = "SELECT PI()*"+n;
ps = con.prepareStatement(sql);
rs = ps.executeQuery();
while(rs.next())
{
double pi = Double.parseDouble(rs.getString(1));
out.println("<html>");
out.println("(pi)*("+num+") = "+pi);
out.println("</html>");
}
}
}
catch(SQLException sx)
{
out.println(sx);
}
catch(ClassNotFoundException cx)
{
out.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>mysqlMathematicalFunction</display-name> <servlet> <servlet-name>MysqlPiServlet</servlet-name> <servlet-class>MysqlPiServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>MysqlPiServlet</servlet-name> <url-pattern>/MysqlPiServlet</url-pattern> </servlet-mapping> </web-app>
Output
When you will execute the above example you will get the output as :
1.
2. When you will entered the value like as :
3. You will get the output as :
4. When you will not give any value like as :
5. You will get the output as :
[ 0 ] Comments