The Query ‘Alias’ will create an alias(Subsitute) of an column name and the reference of column will use to fetch output.
As mentioned we need to make an table named ’emp’ into a database named ‘dbase’ within the reference of Mysql(php myAdmin).after that all the required java packages should have been imported in the starting of program.then after we make a class named ‘JavaServletMySqlAlias’ extends the ‘HttpServlet’. next step will be to use serviceMethod() this method help to getting request call the doGet() for Get a Request. next step will be to load driver with the object of ‘resultset’ some variable are also to be declared like Connection(this variable help to make connection between database and source code for accessing the data from database,Resultset this will does the job to present output table from given query,PreparedStatement will help to execute the selected Query like executeQuery() as (SELECT name, job FROM emp as DV).and in the last step we use doGet() Method to present output on a web browser.
Now on a web browser the Output will be shown as normal but in efficient mode if we need to present The result we will use some kind of ‘HTML’ Coding tags which convert the normal Output into a designer Look or in a tabular form.
EXAMPLE
JavaServletMySqlAlias
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 JavaServletMySqlAlias 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 name, job FROM emp as DV");
rs = ps.executeQuery();
String title = "Employee's Data In Alias Mode";
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>Name</th><th>Job</th>\n"+ "</body> </html>");
while(rs.next())
{
String nm = rs.getString("name");
String jb = rs.getString("job");
disp.println("<tr><td align=\"center\">"+ nm + "<td align=\"center\">" + jb +"</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>JavaServletMySqlAlias</servlet-name>
<servlet-class>JavaServletMySqlAlias</servlet-class>
</servlet>
<!-- servlet mapping -->
<servlet-mapping>
<servlet-name>JavaServletMySqlAlias</servlet-name>
<url-pattern>/JavaServletMySqlAlias</url-pattern>
</servlet-mapping>
Dinesh Thakur holds an B.C.A, MCDBA, MCSD certifications. Dinesh authors the hugely popular