Does Chartio support Joins across Tables?

Yes. Chartio automatically detects foreign key relations between your tables when it imports your schema and joins are automatically built into your queries when dragging columns from related tables in the chart creator.

If you're using a MySQL MyISAM database the foreign keys are not explicitly stored and therefore cannot be automatically detected by Chartio. You will need to manually specify the joins in the schema editor for your database. Read more about manually setting up foreign keys here.