Query Motivation for Cross Joins Say we have two tables 'Vendors' and 'Invoices'. 
Then I understand a reason for doing a left join of
'Vendors' with ' Invoices'  along the VendorID column is to obtain information on Vendors without Invoices. A right join is basically a left
join with tables interchanged (This is the main motivation,right)?

But I cannot see a general motivation from cross joins in this sense,
i.e., if I am given tables Vendors, Invoices joined along VendorID like above, what information is it that Vendors Cross Join allows me to obtain that I cannot obtain through a left join, or otherwise?

Thanks.
A CROSS JOIN gives you the Cartesian product of all the rows in the two tables and then applies any filtering from the WHERE clause. It rarely serves a purpose for your more common table relationships, but there are some occasions where it's handy.

For example, you may need to assign relationships between a static table of Properties and some Items stored in another table. The easiest way to add a new Item and relate it's needed Properties would be to insert the results of a CROSS JOIN between the two tables into a linking table between them. Specific values for those properties could then be added later via other interfaces, but they would have the framework assigned already without having to hard-code the interface.