I have a question regarding SELECT COUNT(*) FROM table_name:
It was said that this returns all the rows that have a non-empty value in the specified column. Here, we use * for all columns.

It is absolutely certain that this statement will return all the rows in the table because at least one of the columns of a row will have a non-empty value?

If the value in a column is NULL, will it be counted as a non-empty or as an empty column?

The way CodeCademy introduces the COUNT() function is just misleading. After defining it as “counts the number of non-empty values in that column”, the first example they give is COUNT(*), no column specified, which is a special case where the COUNT function does count empty values as well…