import java.sql.*;

public class Datenbank {

  public static void main(String[] args) throws SQLException {

   Connection con = DriverManager.getConnection(
   "jdbc:mysql://localhost:3306/bank");

   Statement an = con.createStatement();

   ResultSet rs = an.executeQuery(
   "Select Kontonummer from konto" + "where name = `Martin`");

   while (rs.next())
   {
     System.out.println(rs.getString("Kontonummer"));
   }

   con.close();

  }
}