import java.io.*;
import java.text.*;
import java.util.*;
import java.sql.*;
import java.util.Scanner;

public class Question3 {

public static void main(String args[]) {
    Scanner user_input = new Scanner( System.in );

    int cardnumber, custid;


    System.out.print("Enter your card number: ");
    cardnumber = user_input.nextInt( );
    String url = "jdbc:sqlserver://altebaran.dmst.aueb.gr:1433;" +
                   "databaseName=DB47;user=G547;password=25g489030;";
    Connection dbcon ;
    Statement stmt;
    ResultSet rs;

    try {
        Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
    } catch(java.lang.ClassNotFoundException e){
        System.out.print("ClassNotFoundException: ");
        System.out.println(e.getMessage());
    }

    try {
        dbcon = DriverManager.getConnection(url);
        stmt = dbcon.createStatement();
        rs = stmt.executeQuery("SELECT customerid FROM CreditCard WHERE CreditCard.card_number ="+ cardnumber +";");
        rs.next();
        custid = rs.getInt("customerid");
        String sql1 = "DELETE FROM Transactions WHERE card_number =" + cardnumber + ";";
        String sql2 = "DELETE FROM CreditCard WHERE card_number =" + cardnumber + ";";
        String sql3 = "DELETE FROM Payment WHERE customerid =" + custid + ";";
        stmt.executeUpdate(sql1);
        stmt.executeUpdate(sql2);
        stmt.executeUpdate(sql3);

        rs.close();
        stmt.close();
        dbcon.close();
    } catch (SQLException e) {
        System.out.print("SQLException: ");
        System.out.println(e.getMessage());
    }
}
}