The CData Excel Add-In for Google Sheets 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 c.Name, o.ItemCount, o.TotalCost, o.Date FROM Spreadsheet1_Customers c INNER JOIN Spreadsheet1_Orders o ON c.Id = o.CustomerId

Left Join

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

 SELECT c.Name, o.ItemCount, o.TotalCost, o.Date FROM Spreadsheet1_Customers c LEFT JOIN Spreadsheet1_Orders o ON c.Id = o.CustomerId