The CData Excel Add-In for Square 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 Locations.Name, Payments.NetSalesMoneyAmount FROM Locations, Payments WHERE Locations.Locationid = Payments.LocationId

Left Join

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

SELECT Locations.Name, Payments.NetSalesMoneyAmount FROM Locations LEFT OUTER JOIN Payments ON Locations.LocationId=Payments.LocationId