1) Always use fully qualified names.
selecting from ‘2016’ may work initially as the engine returns the first object it finds with this name (which just so happens to be in the calendar dimension).
However after a time there may be a customer-number ‘2016’ (in the customer dimension) that will be returned erroneously.
2) A Tuple marks the co-ordinates of the data to be returned.
A list of comma separated dimensions that intersect on the required data. EG:
(customer 123, date 10/07/2016, sales-item 456).
3) A Set is a list of related objects
EG:{date 10/07/2016, date 11/07/2016, date 12/07/2016}. A Set can be a list of Tuples.
Database Consultant 