JSF :: Creating Primefaces 4.0 Charts From Database Objects

I'm trying to create a simple bar chart from integer values (measuring number of bulldozers) stored in a mySql DB, in the following schema:

Integer rigId PK;
Integer rigQty;
Date recordDate;
String country FK;

I want to plot the date on the x-axis and quantity on y-axis. I can't seem to find any examples of how to render charts from a database. I just find the generic Primefaces 4.0 examples which uses static data like this:

private void createCategoryModel() { // category chart
categoryModel = new CartesianChartModel();
ChartSeries boys = new ChartSeries();
boys.setLabel("Boys");

[Code] ....

I'm really not sure how to adapt the above to a database method nor have any web searches produced useful examples. I tried something like this, but how to find examples or the type of methods I need to use to create a bar graph from Db values:

@ManagedBean(name = "chartb")
@SessionScoped
public class BarChartBean {
private final Map<Integer, Map<String, Number>> rigNums = new HashMap<>();
// private final Map<Integer, Map<String, Number>> HorasOrcadasPorFunci = new HashMap<>();
private CartesianChartModel cartesianChartModel;

[Code] ....