The CData Cmdlets PowerShell Module 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