MySQL分组查询,前3条数据

SELECT
	tpn.news_id,
	tpn.title,
	tpn.news_group_id,
	tpn.send_date
FROM
	t_pm_news tpn
WHERE
	3 > (
		SELECT
			COUNT(*)
		FROM
			t_pm_news t
		WHERE
			tpn.news_group_id = t.news_group_id AND tpn.send_date <= t.send_date
	)

注：时间相同可能会有误差