private void checkForDBDriver() {
  try {
      //Check if the database driver is available in the current classpath.
      // According to your database you can for example use one of these drivers:

      //Oracle
      Class.forName("oracle.jdbc.driver.OracleDriver");

      //DB2
      Class.forName("com.ibm.db2.jdbc.app.DB2Driver");

      //Microsoft SQL
      Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver");

      //mysql		
      Class.forName("com.mysql.jdbc.Driver");

      //Derby
      Class.forName("org.apache.derby.jdbc.ClientDriver");

      //PostgreSQL
      Class.forName("org.postgresql.Driver");

      //hSQLDb
      Class.forName("org.hsqldb.jdbcDriver");

    } catch (ClassNotFoundException e) {
	throw new RuntimeException("Database driver not found!");
    }
}

private Graph2D createGraphFromDB() {
checkForDBDriver();
Connection con = null;
    try {
      //connect to the database with username and password
      //according to your database for example use one of the following options:

      //Oracle
      con = DriverManager.getConnection(
		"jdbc:oracle:thin:@<serverip>:<port>:<sid>", "<username>", "<password>");

      //DB2
      con = DriverManager.getConnection(
		"jdbc:db2://<serverip>:<port>/<databaseName>", "<username>", "<password>");

      //Microsoft SQL
      con = DriverManager.getConnection(
		"jdbc:microsoft:sqlserver://<serverip>:<port>/<databaseName>", "<username>", "<password>");

      //mysql
      con = DriverManager.getConnection(
		"jdbc:mysql://<serverip>:<port>/<databaseName>", "<username>", "<password>");

      //derby
      con = DriverManager.getConnection(
		"jdbc:derby://<serverip>:<port>/<databaseName>", "<username>", "<password>");

      //PostgreSQL
      con = DriverManager.getConnection(
		"jdbc:postgreesql://<serverip>:<port>/<databaseName>", "<username>", "<password>");

      Graph2D graph = createGraph(con);
      return graph;
    }
    catch (SQLException e) {
	throw(new IllegalStateException("Could not create connection to database: " + e.getMessage()));
    }
    finally {
      if (con != null) {
        try {
          con.close();
        } catch (SQLException e) {
          e.printStackTrace();
        }
      }
}
    }

private Graph2D createGraph(Connection con) throws SQLException {
    Statement stmt = con.createStatement();

    //create an empty graph 
    Graph2D graph = new Graph2D();
    //create a root node
    Node company = graph.createNode();
    graph.getRealizer(company).getLabel().setText("MyCompany");

    //query some data
    ResultSet rs = stmt.executeQuery("SELECT ID, NAME FROM DEPARTMENT");

    HashMap departmentID2Node = new HashMap();
    while (rs.next()) {
      //create a node for each department
      Node department = graph.createNode();
      NodeRealizer realizer = graph.getRealizer(department);
      //set the label of this node
      realizer.getLabel().setText(rs.getString("NAME"));
      //some style customization
      realizer.setFillColor(Color.RED);

      //create an edge from root to this node
      graph.createEdge(company, department);

      //store the node with its according ID for easy access when creating edges later
      departmentID2Node.put(rs.getString("ID"), node);
    }

    rs = stmt.executeQuery("SELECT NAME, DEPARTMENT_ID FROM EMPLOYEE");
    while (rs.next()) {
      //create a node for each employee
      Node employee = graph.createNode();
      NodeRealizer realizer = graph.getRealizer(employee);
      realizer.getLabel().setText(rs.getString("NAME"));
      realizer.setFillColor(Color.BLUE);

	//create an edge between the department and the employee
      Node department = (Node) departmentID2Node.get(rs.getString(("DEPARTMENT_ID")));
      if(department != null) {
        graph.createEdge(department, employee);
      }
    }
    rs.close();
    stmt.close();
    return graph;
  }

//view is of type Graph2DView
view.setGraph2D(createGraphFromDB());