import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;


public class Testklasse {

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

    Connection con = null;
    String driver = "org.postgresql.Driver";
    String DB_SERVER = "obiwan-edu.iis.uni-hildesheim.de:5433";
    String DB_NAME = "WiSe_DBAE_04";
    String password = "34789";
    String user = "WiSe_Gruppe_04";
    String url = "jdbc:postgresql://" + DB_SERVER+ "/" + DB_NAME;

    try {

        Class.forName(driver);

        con = DriverManager.getConnection(url, user, password);
        PreparedStatement pstmt;

        pstmt = con.prepareStatement("SELECT count(*) FROM person WHERE " +
        "nationalitaet = 'USA' AND person_id" +
        " IN ( select person_id from musiker)");
        ResultSet rs = pstmt.executeQuery();
        while(rs.next()) {
            System.out.println(rs.getString(1));

        }
        rs.close();
        pstmt.close();
        con.close();
    } catch (ClassNotFoundException exc) {
        // TODO Auto-generated catch block
        exc.printStackTrace();
    }



}
}