The CData ADO.NET Provider for TaxJar supports standard SQL joins like the following examples.

Inner Join

An inner join selects only rows from both tables that match the join condition:

SELECT o.UserID, o.TransactionDate, o.Provider, ol.ID FROM Orders o INNER JOIN OrderLineItems ol ON o.TransactionID = ol.TransactionID

Left Join

A left join selects all rows in the FROM table and only matching rows in the JOIN table:

SELECT o.UserID, o.TransactionDate, o.Provider, ol.ID FROM Orders o LEFT JOIN OrderLineItems ol ON o.TransactionID = ol.TransactionID