Counting rows where a timestamp is less than 24 hours old

Question

For the query below, how could I count the number of rows where datesent is less than 24 hours old? (The field datesent is a timestamp).

T

Answer 1

$message="select count(1)
from privatemessage
where datesent>=date_sub(now(), 24 hours)
and recipient='$u'"

http://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html#function_date-add