Can you please brief us more about your requirement along with an example or pictorial representation so that we can understand your scenario better and help you out?
It seems like the x-values that are passed to the chart are null. X-Values can either be numeric or date-time. Please take a look at this sample project with data for an example on drilldown chart with data from database. You can change the structure of the database table according to your requirements, update query accordingly and pass datapoints to the chart-options.
Can you please share some pictorial representation of your requirement, so that we can understand the scenario better and suggest you an appropriate solution?