Question

How do I get my program to ask the user to re enter the correct information if the information entered does not match the database records? When I run my program it does let me know that the information entered does not match but it does not ask me to enter the information again.

package MailMeSQL;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.util.Scanner;

import com.mysql.cj.jdbc.JdbcConnection;

public class mailmeMain {

   public static void main(String[] args) {

       Scanner scanner = new Scanner(System.in);

       System.out.println("Please Enter your Email:");

       String email = scanner.nextLine(); //get email from user

       System.out.println("Please Enter your pin:");

       int pin = scanner.nextInt(); //get pin from user

       printUserData(email, pin); // call printUserData method with email and pin

   }

   private static void printUserData(String email, int pin) {

       String url = "jdbc:mysql://localhost:3306/mailme";

       String username = "root";

       String password = "Chicago#71519";

       Connection connection = null;

       PreparedStatement preparedStatement = null;

       ResultSet result = null;

       try {

           connection = DriverManager.getConnection(url, username, password);

           String query = "select * from tenant_profile where email=? and pin=?";

           preparedStatement = connection.prepareStatement(query); // prepare the sql query

           preparedStatement.setString(1, email); // bind email value

           preparedStatement.setInt(2, pin); //bind pin value

           result = preparedStatement.executeQuery(); //execute query

                           while (result.next()) { //fetch result

               System.out.println("Email=" + result.getString("email") + ",pin=" + result.getString("pin")

                       + ",Package=" + result.getString("packages"));

           }

       } catch (SQLException e) {

           e.printStackTrace();

       } finally {

           if (result != null)

               try {

                   connection.close();

                   result.close();

               } catch (SQLException e) {

                   e.printStackTrace();

               }

       }

   }

}

Answer 1

We can add a simple while in the code where we are taing from the user and we should use and declare the function as int so that we can return a value that will indicate if the database exist or not , if data exist in database we will exit the loop and if data does not exist in database we will repeat the loop.

package MailMeSQL;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.util.Scanner;

import com.mysql.cj.jdbc.JdbcConnection;

public class mailmeMain {

   public static void main(String[] args) {

       Scanner scanner = new Scanner(System.in);
       int m=0;
       while(m!=0){

       System.out.println("Please Enter your Email:");

       String email = scanner.nextLine(); //get email from user

       System.out.println("Please Enter your pin:");

       int pin = scanner.nextInt(); //get pin from user

       m=printUserData(email, pin); // call printUserData method with email and pin
       
       }

   }

   private static int printUserData(String email, int pin) {

       String url = "jdbc:mysql://localhost:3306/mailme";

       String username = "root";

       String password = "Chicago#71519";

       Connection connection = null;

       PreparedStatement preparedStatement = null;

       ResultSet result = null;

       try {

           connection = DriverManager.getConnection(url, username, password);

           String query = "select * from tenant_profile where email=? and pin=?";

           preparedStatement = connection.prepareStatement(query); // prepare the sql query

           preparedStatement.setString(1, email); // bind email value

           preparedStatement.setInt(2, pin); //bind pin value

           result = preparedStatement.executeQuery(); //execute query

                           while (result.next()) { //fetch result

               System.out.println("Email=" + result.getString("email") + ",pin=" + result.getString("pin")

                       + ",Package=" + result.getString("packages"));

           }

       } catch (SQLException e) {

           e.printStackTrace();

       } finally {

           if (result != null)

               try {

                   connection.close();

                   result.close();

               } catch (SQLException e) {

                   e.printStackTrace();

               }

       }
       if(result == null)
       {
           return 0;
       }
       else{
           return 1;}
       }
       

   }

}