Mysql ALIAS name for COLUMN using java servlet

In this section you will learn about how can you give an alias name to a column.

Mysql ALIAS name for COLUMN using java servlet

In this section you will learn about how can you give an alias name to a column.

ALIAS name can be given to the column name. ALIAS is used when your column name is too long or complex. So It is good to give an alias name to the column. ALIAS name could be given any thing but it should be used for to give a small name. Now we have to use it with select statement using java servlet. So, I create a class named MysqlAliasColumnServlet 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 since we have to use a SQL query so at first we will have to make a connection between java code and database system. I am using here Mysql so in the example given below I am loading the driver of mysql and make a connection by using the getConnection() method of DriverManager class. It returns a Connection. Now I have a table 'employee' that I had created in mysql earlier. So I did not need to create a table here. Further I passed the query "SELECT name AS nm FROM employee" 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 an object of ResultSet interface from which I extract the records.

Example :

MysqlAliasColumnServlet.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 MysqlAliasColumnServlet extends HttpServlet {
	Connection con;
	PreparedStatement ps;
	ResultSet rs;

	public void doGet(HttpServletRequest req, HttpServletResponse res)
			throws IOException, ServletException {
		PrintWriter pw = res.getWriter();
		res.setContentType("text/html");
		String driver = "com.mysql.jdbc.Driver";
		String url = "jdbc:mysql://192.168.10.13/data";
		String uid = "root";
		String psw = "root";
		String sql = "SELECT name AS nm FROM employee";
		try {
			Class.forName(driver);
			con = DriverManager.getConnection(url, uid, psw);

			ps = con.prepareStatement(sql);
			rs = ps.executeQuery();
			
			pw.println("<table>");
			pw.println("<tr><td>nm</td></tr>");
			while (rs.next()) {
				String name = rs.getString(1);
				pw.println("<tr>");
				pw.println("<td>" + name + "</td>");
				pw.println("</tr>");
			}
			pw.println("</table><br>");

		} 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>join</display-name>

<servlet>
<servlet-name>MysqlAliasColumnServlet</servlet-name>
<servlet-class>MysqlAliasColumnServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>MysqlAliasColumnServlet</servlet-name>
<url-pattern>/MysqlAliasColumnServlet</url-pattern>
</servlet-mapping>

</web-app>

Output

When you will execute the above example you will get the output as :

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