The main difference is that using ROWNUM in the general case requires a HAVING clause, which requires a GROUP BY clause. Doing that may require the use of aggregation functions in the SELECT clause, which is, I think you'd agree, a fundamental difference.

The fact that ROWNUM (and ROWID, but that's not the topic here) is assigned before the ORDER BY clause is executed is another major issue. 

SELECT foo
  FROM bar
 ORDER BY 1
 LIMIT 5, 10

[download]
versus 
SELECT foo
  FROM (
        SELECT foo
          FROM bar
         ORDER BY 1
       )
 GROUP BY 1
 HAVING ROWNUM >= 5
    AND ROWNUM <= 10

[download]

I know which I'd rather work with ...

Being right, does not endow the right to be rude; politeness costs nothing.
Being unknowing, is not the same as being stupid.
Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence.
Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.

In reply to Re^6: Should it be database independent? by dragonchild
in thread Should it be database independent? by szabgab

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