This function ‘Comparison Operator’ will check the comparison between two expressions.
First i made a table named ‘sal’ with required fields and values into a database named ‘dbase’ within the reference of mySql(php myAdmin).then i import all the java packages from the java library. I made a class named ‘MySqlComparisonOperatorJavaServlet’ extends the ‘HttpServlet’. I use serviceMethod() which is use to getting the request from the doGet()method for output on a web server. Then i loaded all the required drivers for database accessing. I use variables that will be used to database connectivity. First i declare ‘connection’ (this variable will create a link between a database and the java code). I declare ‘resultSet'(this variable will be the responsible for getting value from required fields like columns and rows).then i declare ‘preparedStatement’ this variable will use to execute the selected query like executeQuery() as (SELECT last_name, salary FROM sal WHERE salary <= 8000″). Now i use the doGet()Method which will bring the output on web browser.
To getting output in a tabular form on a web browser i use ‘HTML’ code and tags that will bring output in a manner way.
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 MySqlComparisonOperatorJavaServlet 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 last_name, salary FROM sal WHERE salary <= 8000");
rs = ps.executeQuery();
String title = "Employee's Info With Comparison Condition";
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" + "<h3 align=\"center\">" + title + "</h3>\n" + "<ul>\n" +
"<table width=\"50%\" border=\"1\" align=\"center\">\n" + "<th>Last Name</th><th>Salary</th>\n"+ "</body> </html>");
while(rs.next())
{
String l_name = rs.getString("last_name");
int sal = rs.getInt("salary");
disp.println("<tr><td align=\"center\">"+ l_name + "<td align=\"center\">"+ sal +"</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>MySqlComparisonOperatorJavaServlet</servlet-name>
<servlet-class>MySqlComparisonOperatorJavaServlet</servlet-class>
</servlet>
<!-- servlet mapping -->
<servlet-mapping>
<servlet-name>MySqlComparisonOperatorJavaServlet</servlet-name>
<url-pattern>/MySqlComparisonOperatorJavaServlet</url-pattern>
</servlet-mapping>
Dinesh Thakur holds an B.C.A, MCDBA, MCSD certifications. Dinesh authors the hugely popular