The Computation of Operator Precedence rule Condition.
First i made a table named ‘reg’ into a database named ‘dbase’ within the reference of mySql(php myAdmin). In the starting of Program, we need to import all the Required Packages from the java library. Then to declare a class named ‘MySqlPrecedenceRule’ which is been extends ‘HttpServlet’. After then we have to use serviceMethod() which is responsible for the Getting request for Output. Then load drivers and create an Object of resultSet which, will useful to show the table result as an Output. Connection variable also to be declare for interact between database and actual code as like in between frontend and backend. Now on other hand preparedStatement will be use for executing query like executeQuery() as (SELECT last_name, job_id, salary FROM reg WHERE job_id = ‘it_prog’OR job_id = ‘manager’AND salary > 12000). And to fetch the result on web browser doGet() method will be initialize.
To feel look good the result we use a tabular form concept. For this kind of requirement, we use ‘HTML’ coding and some of tags to use Output in Designer look to show on a web browser.
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 MySqlPrecedenceRule 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 last_name, job_id, salary FROM reg WHERE job_id = 'it_prog'OR job_id = 'manager'AND salary > 12000");
rs = ps.executeQuery();
String title = "Employee's Info With Using of Precedence Rule Query";
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>Last Name</th><th>Job Id</th><th>Salary</th>\n"+ "</body> </html>");
while(rs.next())
{
String l_name = rs.getString("last_name");
String j_id=rs.getString("job_id");
int sal=rs.getInt("salary");
disp.println("<tr><td align=\"center\">" + l_name +"<td align=\"center\">" + j_id +"<td align=\"center\">" + sal +"</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>MySqlPrecedenceRule</servlet-name>
<servlet-class>MySqlPrecedenceRule</servlet-class>
</servlet>
<!-- servlet mapping -->
<servlet-mapping>
<servlet-name>MySqlPrecedenceRule</servlet-name>
<url-pattern>/MySqlPrecedenceRule</url-pattern>
</servlet-mapping>
Dinesh Thakur holds an B.C.A, MCDBA, MCSD certifications. Dinesh authors the hugely popular