The CData ADO.NET Provider for FHIR 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 c.[name-given], c.[address-city], o.status, o.id FROM Patient c INNER JOIN SupplyDelivery o ON o.[patient-reference] = ('Patient/' + c.[id] )

Left Join

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

 SELECT c.[name-given], c.[address-city], o.status, o.id FROM Patient c LEFT JOIN SupplyDelivery o ON o.[patient-reference] = ('Patient/' + c.[id] )