The CData ADO.NET Provider for Zoho CRM 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 Accounts.AccountName, Contacts.FirstName, Contacts.LastName FROM Accounts, Contacts WHERE Accounts.AccountId=Contacts.AccountId

Left Join

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

SELECT Accounts.AccountName, Contacts.FirstName, Contacts.LastName FROM Accounts LEFT OUTER JOIN Contacts ON Accounts.AccountId=Contacts.AccountId