What's the most efficient way to select the last n rows in a table without changing the table's structure?

Question

What\'s the most efficient way to select the last n number of rows in a table using mySQL? The table contains millions of rows, and at any given time I don\'t know how large

Answer 1

(Similar to "marco"s answer,)
my fav is the max()-function of MySQL too, in a simple one-liner, but there are other ways of sure:

SELECT whatever FROM mytable WHERE id > (SELECT max(id)-10 FROM mytable);

... and you get "last id minus 10", normally the last 10 entries of that table.

It's a short way, to avoid the a error 1111 ("Invalid use of group function") not only if there is a auto_increment-row (here id).
The max()-function can be used many ways.