The Marketo Adapter 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 l.FirstName, l.LastName, a.LinkURL, a.UserAgent FROM Leads l INNER JOIN Activities_ClickLink a ON l.Id = a.LeadId

Left Join

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

 SELECT l.FirstName, l.LastName, a.LinkURL, a.UserAgent FROM Leads l LEFT JOIN Activities_ClickLink a ON l.Id = a.LeadId