In this tutorial you will learn about how to use mysql's is nll operator with servlet.
MySql IS NULL Operator With Servlet Example
In this tutorial you will learn about how to use mysql's is nll operator with servlet.
IS NULL operator checks that a value is null or not, if the statement is getting true then it returns 1, otherwise returns 0.
Example :
To use this operator 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 MysqlIsNullOprtr.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 is null operator 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 empId IS NULL, deptId IS NULL FROM userInfo".
MysqlIsNullOprtr.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 MysqlIsNullOprtr 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 empId IS NULL, deptId IS NULL FROM userInfo";
ps= con.prepareStatement(sql);
rs= ps.executeQuery();
out.println("<html>");
out.println("<table border=1>");
out.println("<th>empId IS NULL</th><th>deptId IS NULL</th>");
while(rs.next())
{
String empId = rs.getString("empId IS NULL");
String deptId = rs.getString("deptId IS NULL");
out.println("<tr>");
out.println("<td align=middle>"+empId+"</td>");
out.println("<td align=middle>"+deptId+"</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>MysqlIsNullOprtr</servlet-name> <servlet-class>MysqlIsNullOprtr</servlet-class> </servlet> <servlet-mapping> <servlet-name>MysqlIsNullOprtr</servlet-name> <url-pattern>/MysqlIsNullOprtr</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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