Understanding the differences between CUBE and ROLLUP

Question

My assignment asked me to find out \"how many invoices are written for each date?\"

I was a little stuck and asked my professor for help. She emailed me a query that

Answer 1

This is because you only have one column that you are grouping by.

Add Group by InvoiceDt, InvoiceCountry (or whatever field will give you more data.

With Cube will give you a Sum for each InvoiceDt and you will get a Sum for each InvoiceCountry.