The Nth row in a table

If the rows in the table aren't in any order—and they aren't, not in any relational database system—then how do you know which one is the Nth one? You don't.

Therefore, pick any row of the table, and just pretend it's the Nth.

Of course, if you want to retrieve the Nth row based on the values of some column, then that's a different question. It has an SQL solution, too. But I'm not sure you have this situation.