[PHP] trying to get a certain num of rows in mysql

[Pablo Oliva]

When doing a select query, is there any way to specify which rows you
want "selected", as in rows 1 through 40, and then 40 - 80 on the next
query.  I've been searching through the manual but can't find anything.
Should this be done through a php script instead, or is there a native
(mysql) command/clause for this?