In this tutorial you will learn about how to use mysql's isnll() function with servlet.
MySql ISNULL() Function Example With Servlet
In this tutorial you will learn about how to use mysql's isnll() function with servlet.
ISNULL() function checks that a value is null or not, if the value is getting to null then it returns 1, otherwise returns 0.
Example :
To use this function in the example first I created a table using the mysql database system named 'userInfo' and put the values in their respective fields. Since we have to use this operator with servlet so I created a servlet class named MysqlIsNullFunction.java which extends the class HttpServlet to support the http functionality to servlet, into which I defined the doGet() method into which the object's of HttpServeltRequest and HttpServletResponse are created. And because of we have to use mysql's isnull() function in servlet so we are required to connect with the database package (here I am using MySql) that's why in this example I perform the database connectivity with servlet using the java.sql package in java. To use this operator I used the query "SELECT ISNULL(empId) FROM userInfo".
MysqlIsNullFunction.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 MysqlIsNullFunction extends HttpServlet
{
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException
{
response.setContentType("text/html");
PrintWriter out= response.getWriter();
String className= "com.mysql.jdbc.Driver";
String url= "jdbc:mysql://192.168.10.13/data";
String user= "root";
String password= "root";
Connection con;
PreparedStatement ps;
ResultSet rs;
try
{
Class.forName(className);
con= DriverManager.getConnection(url, user, password);
String sql= "SELECT ISNULL(empId) FROM userInfo";
ps= con.prepareStatement(sql);
rs= ps.executeQuery();
out.println("<html>");
out.println("<table border=1>");
out.println("<th>empId ISNULL()</th>");
while(rs.next())
{
String empId = rs.getString("ISNULL(empId)");
out.println("<tr>");
out.println("<td align=middle>"+empId+"</td>");
out.println("</tr>");
}
out.println("</table>");
out.println("</html>");
}
catch(SQLException sx)
{
out.println(sx);
}
catch(ClassNotFoundException cx)
{
out.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>mysqlComparisonFunctionAndOperator</display-name> <servlet> <servlet-name>MysqlIsNullFunction</servlet-name> <servlet-class>MysqlIsNullFunction</servlet-class> </servlet> <servlet-mapping> <servlet-name>MysqlIsNullFunction</servlet-name> <url-pattern>/MysqlIsNullFunction</url-pattern> </servlet-mapping> </web-app>
Output :
Data in the database table is as :
When you will execute the above example you will get the output as :
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