The CData ADO.NET Provider for Shopify 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 Customers.MultipassIdentifier, Orders.TotalPrice FROM Customers, Orders WHERE Customers.Id=Orders.CustomerId

Left Join

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

SELECT Customers.MultipassIdentifier, Orders.TotalPrice FROM Customers LEFT OUTER JOIN Orders ON Customers.Id=Orders.CustomerId