The CData Excel Add-In for Confluence 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 Pages.Title, Spaces.Name FROM Contents, Spaces WHERE Pages.SpaceKey=Spaces.Key

Left Join

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

SELECT Pages.Title, Spaces.Name FROM Contents LEFT OUTER JOIN Spaces ON Pages.SpaceKey=Spaces.Key