This will Returns the non-negative square root of numeric expression.
First i made a database named ‘dbase’ within the reference of mySql(php myAdmin).Then after, I import all java packages from java library as program need. Here i made a class named ‘MySqlSQRTFunction’, which extends ‘HttpServlet’. I use service()Method that will help to getting the request from doGet()Method for output on web browser. Then I loaded all the required Drivers that will help to accessing Database. After then i declare variable first i use ‘connection’ variable that will create a link between database and the actual code(frontend and the backend).Other variable is ‘ResultSet’ that will help to fetch value from the columns and rows as required query. The next variable is ‘preparedStatement’ that will use to executing the selected Query like executeQuery as (Select SQRT(7)).I use doGet()Method in last instance that will bring the output on web browser.
I Use ‘HTML’ code and some tags, which will show the output in tabular form on the web browser.
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 MySqlSQRTFunction 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 SQRT(7)");
rs = ps.executeQuery();
String title = "Using SQRT 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</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>MySqlSQRTFunction</servlet-name>
<servlet-class>MySqlSQRTFunction</servlet-class>
</servlet>
<!-- servlet mapping -->
<servlet-mapping>
<servlet-name>MySqlSQRTFunction</servlet-name>
<url-pattern>/MySqlSQRTFunction</url-pattern>
</servlet-mapping>
Dinesh Thakur holds an B.C.A, MCDBA, MCSD certifications. Dinesh authors the hugely popular