The CData ODBC Driver for ActiveCampaign 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 Deals.Id, Deals.ActivityCount, Deals.Currency, Deals.CustomerAccount FROM Deals INNER JOIN Accounts ON Deals.AccountId = Accounts.Id

Left Join

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

 SELECT Deals.Id, Deals.ActivityCount, Deals.Currency, Deals.CustomerAccount FROM Deals LEFT JOIN Accounts ON Deals.AccountId = Accounts.Id