Guided Project: Answering Business Questions using SQL

In the Guided Project: Answering Business Questions using SQL
to answer which genre is the most popular in USA, DQ used count(uts.invoice_line_id) tracks_sold,
but invoice_line has quantity field, wouldn’t it be correct to use count(il.quantity) to check most genres sold?

It’s been too long since I did that project so I don’t recall very clearly the specific details of each field.

The way I personally did it was I counted the number of unique customers of each genre (COUNT(customer_id)), by using the customer_id column in the invoice table.

Which means my resulting table displayed the number of customers of each genre, and not the absolute number of tracks sold.

I suppose you could indeed also alternatively count the no. of track_id, or use the quantity column to calculate the absolute number of tracks.