SELECT a.*
, a.attending-b.attending new_actual_attending
FROM
(SELECT x.*
, COUNT(*) rank
FROM event x
JOIN event y
ON y.eid = x.eid
AND y.start_time <= x.start_time
GROUP
BY eid, start_time
) a
LEFT
JOIN
(SELECT x.*
, COUNT(*) rank
FROM event x
JOIN event y
ON y.eid = x.eid
AND y.start_time <= x.start_time
GROUP
BY eid, start_time
) b
ON b.eid = a.eid
AND b.rank = a.rank - 1;
+-----+------------+-----------+------------------+------+----------------------+
| eid | start_time | attending | actual_attending | rank | new_actual_attending |
+-----+------------+-----------+------------------+------+----------------------+
| 1 | 2013-06-08 | 29 | NULL | 1 | NULL |
| 2 | 2013-06-09 | 72 | NULL | 1 | NULL |
| 2 | 2013-06-16 | 104 | NULL | 2 | 32 |
| 3 | 2013-06-07 | 224 | NULL | 1 | NULL |
| 3 | 2013-06-14 | 222 | NULL | 2 | -2 |
+-----+------------+-----------+------------------+------+----------------------+
http://sqlfiddle.com/#!2/43f2c5/2
는 조언을 sqlfiddle – Strawberry
지금 제공, 감사를 제공하는 것을 고려 : 여기
는 예로서 sqlfiddle이다. –