Can we sort by multiple columns at once? And what does it mean? Assume, we firstly sort by one column. If there are some matches in this column, then sorting by another column will sort within this sub-group.

To make SQL sort by multiple columns at once just write ORDER BY followed by column names you want to sort by separated with a comma. For example, we can sort the entire audi_cars table firstly by engine size (enginesize) in descending order and then by price in ascending.