The Oracle Eloqua 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 Contact.Name, Activity_EmailClickThrough.CreatedAt FROM Contact, Activity_EmailClickThrough WHERE Contact.ID=Activity_EmailClickThrough.ContactID

Left Join

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

SELECT Contact.Name, Activity_EmailClickThrough.CreatedAt FROM Contact LEFT OUTER JOIN Orders ON Contact.ID=Activity_EmailClickThrough.ContactID