The CData Excel Add-In for Microsoft Planner 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 Tasks.Title, Buckets.Name FROM Tasks INNER JOIN Buckets ON Tasks.BucketId = Buckets.BucketId

Left Join

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

 SELECT Tasks.Title, Buckets.Name FROM Tasks LEFT JOIN Buckets ON Tasks.BucketId = Buckets.BucketId