Counting posts per day

1

My table stores the Unix timestamp of each forum post. I want to be able to graph [number of posts in this day] VS [days since epoch]. My first step was to be able to detect which posts were from the same day:


SELECT ROUND(time / 86400) as daysSinceEpoch, time
FROM posts 
ORDER BY daysSinceEpoch
ASC

This gives me:


daysEpoch  time
13378 	1155850620
13378 	1155850620
13378 	1155850920
13378 	1155851040
13378 	1155851160
13386 	1156568400
13387 	1156629120
13387 	1156629180
13387 	1156629180

Now I don’t know how to complete the query to give me:


daysEpoch  numPostsInThisDay
13378        5
13386        1
13387        3