problem from registering a data in database with servlet

Expert:DARE
Hi Rose,
i created a servlet to validates ten user details in the database, if present it should return "You have already registered" but if not it should take all the user's details and submit into database.

but it'll first insert the details in the database for the first time you open your browser but if you try to insert with the same details later then it will complain.

please find turn this for me

Answers

Hi Friend,

Try the following code:

1)addUser.jsp:

<html>
<head>
</head>
<body>
<form name="userform" method="post" action="../AddUser">
<br><br><br>
<table align="center" width="300px" style="background-color:#EDF6EA;border:1px solid #000000;">
<tr><td colspan=2 style="font-weight:bold;" align="center">Add User</td></tr>
<tr><td colspan=2 align="center" height="10px"></td></tr>
<tr>
<td style="font-weight:bold;">First Name</td>
<td><input type="text" name="first_name" value=""></td>
</tr>
<tr>
<td style="font-weight:bold;">Last Name</td>
<td><input type="text" name="last_name" value=""></td>
</tr>
<tr>
<td style="font-weight:bold;">UserName</td>
<td><input type="text" name="username" value=""></td>
</tr>
<tr>
<td style="font-weight:bold;">Password</td>
<td><input type="password" name="password" value=""></td>
</tr>

<tr>
<td style="font-weight:bold;">City</td>
<td><input type="text" name="city" rows=5 cols=25></td>
</tr>
<tr>
<td style="font-weight:bold;">State</td>
<td><input type="text" name="state" value=""></td>
</tr>
<tr>
<td style="font-weight:bold;">Country</td>
<td><input type="text" name="country" value=""></td>
</tr>

<tr>
<td></td>
<td><input type="submit" name="Submit" value="Save" style="background-color:#49743D;font-weight:bold;color:#ffffff;"></td>
</tr>
<tr><td colspan=2 align="center" height="10px"></td></tr>
</table>
</form>

</body>
</html>

continue.............

2)Servlet 'AddUser.java':

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.sql.*;
import java.sql.*;
import java.util.*;

public class AddUser extends HttpServlet{

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException,IOException{
response.setContentType("text/html");
PrintWriter out = response.getWriter();

System.out.println("MySQL Connect Example.");
Connection conn = null;
String url = "jdbc:mysql://localhost:3306/";;
String dbName = "register";
String driver = "com.mysql.jdbc.Driver";
String userName = "root";
String password = "root";

String first_name = request.getParameter("first_name").toString();
String lastName = request.getParameter("last_name").toString();
String username = request.getParameter("username").toString();
String pass = request.getParameter("password").toString();
String city = request.getParameter("city").toString();
String state = request.getParameter("state").toString();
String country = request.getParameter("country").toString();

Statement stmt1,stmt2;
try {
Class.forName(driver).newInstance();
conn = DriverManager.getConnection(url+dbName,userName,password);
System.out.println("Connected to the database");

String query1="Select * from user";
stmt1 = conn.createStatement();
ResultSet rs=stmt1.executeQuery(query1);
String value1="",value2="",value3="",value4="",value5="",value6="",value7="";
while(rs.next()){
value1=rs.getString("first_name");
value2=rs.getString("last_name");
value3=rs.getString("username");
value4=rs.getString("password");
value5=rs.getString("city");
value6=rs.getString("state");
value7=rs.getString("country");
}
if((value1.equals(first_name))&&(value2.equals(lastName))&&(value3.equals(username))&&(value4.equals(pass))&&(value5.equals(city))&&(value6.equals(state))&&(value7.equals(country))){
out.println("You have already registered");
}
else{

String query2 = "insert into user set first_name='"+first_name+"',last_name='"+lastName+"',username='"+username+"',password='"+pass+"',city='"+city+"',state='"+state+"',country='"+country+"'";
stmt2 = conn.createStatement();
int i = stmt2.executeUpdate(query2);
out.println("You have registered successfully");
}
conn.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}

continue...

3)In web.xml,do the servlet mapping:

<servlet>
<servlet-name>AddUser</servlet-name>
<servlet-class>AddUser</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>AddUser</servlet-name>
<url-pattern>/AddUser</url-pattern>
</servlet-mapping>

Hope that the above code will help you.

Thanks

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