The Salesforce Pardot 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 p.CampaignId, p.Email, pa.CreatedAt FROM Prospects p INNER JOIN ProspectAccounts pa ON p.ProspectAccountId = pa.Id

Left Join

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

SELECT v.Id, v.ProspectId, v.CreatedAt, vs.PageViewCount, vs.IpAddress FROM Visits v LEFT JOIN Visitors vs ON v.VisitorId = vs.Id