This Function will tell that the Given Expression is Null or Not.
I make a table in database named ‘dbase’ with required fields and values in it. Database is been created in the reference of mySql(php myAdmin).Here i import all the java packages required during the program from java library. Then i make a class named ‘MySqlNOTNULLFunction’ extends the ‘HttpServlet’. Here I use serviceMethod() which will bring the request from doGet()Method for Output. Here the next step will be to load all required drivers for database accessing. Now, i will declare the mandatory variables like ‘connection’ this variable will take over to create a link between the database and the java code. The next one will be the ‘resultSet’ this variable will use to retrieve the value from columns and rows as required the query. The other one will be the ‘preparedStatement’ this variable is must use for the executing selected query like executeQuery as (SELECT 7 IS NOT NULL). Here i use doGet()Method for getting output on the web Browser.
While getting Output on the Web Browser we use ‘HTML’ Code or some of these tags to present Output in tabular form.
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 MySqlNOTNULLFunction 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 7 IS NOT NULL");
rs = ps.executeQuery();
String title = "Using NOT NULL() 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>MySqlNOTNULLFunction</servlet-name>
<servlet-class>MySqlNOTNULLFunction</servlet-class>
</servlet>
<!-- servlet mapping -->
<servlet-mapping>
<servlet-name>MySqlNOTNULLFunction</servlet-name>
<url-pattern>/MySqlNOTNULLFunction</url-pattern>
</servlet-mapping>
Dinesh Thakur holds an B.C.A, MCDBA, MCSD certifications. Dinesh authors the hugely popular