The CData ADO.NET Provider for Microsoft OneNote 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 Groups.displayName, Notebooks.displayName FROM Groups, Notebooks WHERE Groups.Id=Notebooks.GroupId

Left Join

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

SELECT Groups.displayName, Notebooks.displayName FROM Groups LEFT OUTER JOIN Notebooks ON Groups.Id=Notebooks.GroupId