The CData JDBC Driver for Domino 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 n.username, c.color_choice FROM [Notes] n INNER JOIN [color_choice] c ON c.[@unid] = o.[@unid]

Left Join

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

 SELECT n.username, c.color_choice FROM [Notes] n LEFT JOIN [color_choice] c ON c.[@unid] = o.[@unid]