Selecting 'n' MySQL rows

[Anon]

I have a simple forum script, and want to display 50 threads per page. The page only displays the opening thread posts (not the replies), which are flagged in my table with a simple true/false value. So, to select the first 50 openers, I do a

$result = mysql_query(SELECT * FROM posts WHERE op = 1 LIMIT 0,50);

Now, is there any possible way to set the LIMIT offset to get, say, opening posts 51-100 without knowing what the id of the 50th opener was, without going through and counting up to the 51st opener and starting from there?

[Anon]

Yup, change the query to
SELECT * FROM posts WHERE op = 1 LIMIT $offset,50

where offset is where you want it to start.

[Anon]

OK, but what if the offset isn't known?

[tomhath]

Look under the "Articles" tab in this site. There's one about Next/Perv buttons that explains the whole thing.