SQL count(*) and distinct

Question

Why can\'t we use count(distinct *) in SQL? As in to count all distinct rows?

Answer 1

some languajes may not be able to handle 'distinct *' so, if you want the distinction made through many columns you might want to use 'distinct ColumnA || ColumnB' , combining the values before judging if they are different. Be mindful whether your variables are numeric and your database handler can make automatic typecast to character strings.