DerbyDAO (simple)

package od.igor.petrov.derby;

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.ArrayList;

import od.igor.petrov.utils.TestTableBean;

public class DerbyDAO {

    /* ========================================== *
     *     BASIC MANIPULATIONS WITH DATABASE
     * ========================================== */
    protected Connection retrieveConnection() {
        try {
            if (conn == null || conn.isClosed()) {
                Class.forName(DRIVER);
                System.out.println("Driver loaded!");
                conn = DriverManager.getConnection(CONNECTION_URL);
                System.out.println("Connection really opened");
            }
        } catch (ClassNotFoundException e) {
            System.out.println("Problems with driver");
        } catch (SQLException e) {
            System.out.println("Some error");
        } finally {
            System.out.println("Had chance to open connection");
        }
        return conn;
    }

    protected void closeConnection() {
        try {
            if (conn != null) {
                conn.close();
                System.out.println("Closing connection");
            }
        } catch (SQLException e) {
            System.out.println("Failed to close connection");
        } finally {
            conn = null;
        }
    }


    /* =============================================== *
     *                     C R U D
     * =============================================== */
    protected void createTable() {
        try {
            s = retrieveConnection().createStatement();
            if (tableExists()) {
                System.out.println("Found previous version of table\nDropping");
                s.execute(DROP_TABLE);
            }
            s.execute(CREATE_TABLE);
        } catch (SQLException e) {
            System.out.println("Error while creating statement");
        }
    }

    protected boolean tableExists() {
        try {
            s = retrieveConnection().createStatement();
            s.execute(TEST_STATEMENT);
        } catch (SQLException e) {
            String err = (e).getSQLState();
            if (err.equals(ERROR_TABLE_EXISTS)) {
                return false;
            }
        }
        return true;
    }

    public void insertValues(){
        createTable();
        try {
            ps = retrieveConnection().prepareStatement(INSERT_VALUES);
            for (int i = 0; i < 10; i++) {
                ps.setInt(1, i);
                ps.setString(2, "value" + i);
                switch (i%3) {
                case 0:
                    ps.setString(3, "Firm-0");
                    break;
                case 1:
                    ps.setString(3, "Firm-1");
                    break;
                case 2:
                    ps.setString(3, "Firm-2");
                    break;
                default:
                    ps.setString(3, "Dafault");
                    break;
                }
                ps.executeUpdate();
            }
            System.out.println("Inserted some values");
            if (ps != null) {
                ps.close();
            }
        } catch (SQLException e) {
            System.out.println("Error while creating prepared statement");
        } finally {
            ps = null;
            closeConnection();
        }
    }

    public ArrayList<TestTableBean> selectValues(){
        try {
            s = retrieveConnection().createStatement();
            results = s.executeQuery(SELECT_VALUES);
            while (results.next()) {
                result.add(new TestTableBean(results.getInt(1), results.getString(2), results.getString(3)));
            }
            if (results != null) {
                results.close();
            }
        } catch (SQLException e) {
            System.out.println("Some error with getting SQL");
            return null;
        } finally {
            results = null;
            closeConnection();
        }
        return result;
    }

    private static final String DRIVER = "org.apache.derby.jdbc.EmbeddedDriver";
    private static final String DB_NAME = "TestDB";
    private static final String CONNECTION_URL = "jdbc:derby:" + DB_NAME + ";create=true";

    private static final String CREATE_TABLE = "CREATE TABLE TESTTABLE(ID INT NOT NULL, ITEM VARCHAR(10) NOT NULL, FIRM VARCHAR(10) NOT NULL)";
    private static final String INSERT_VALUES = "INSERT INTO TESTTABLE VALUES(?, ?, ?)";
    private static final String SELECT_VALUES = "SELECT * FROM TESTTABLE";
    private static final String DROP_TABLE = "DROP TABLE TESTTABLE";

    private static final String TEST_STATEMENT = "UPDATE TESTTABLE SET ID = 1, ITEM = 'TEST' WHERE 1 = 3";
    private static final String ERROR_TABLE_EXISTS = "42X05";

    private Connection conn = null;
    private Statement s = null;
    private PreparedStatement ps = null;
    private ResultSet results = null;

    private ArrayList<TestTableBean> result = new ArrayList<TestTableBean>();
}