web access database - SharePoint Online - How to pull data from Access Web App to sharepoint

Hi All,
     I have been going through : Key Drawbacks of Access Web Apps

I have a client that im thinking of hosting there CRM and HR in Web Apps.
But not sure if we need to pull some data from the Access database how can this be done?

So let say i would like to show some data from the HR or CRM site based on web apps is there a way do to this via odata/CSOM etc..

Thanks in Advance