mysql 5.8 查询最新一条数据

SELECT * FROM (
SELECT temp.*, @rn := IF(@prev = order_id,@rn + 1,1) AS rn, @prev = 1 FROM
(SELECT * FROM or_task_node ORDER BY created_date DESC) temp
JOIN (SELECT @rn := 0) AS vars
) t
WHERE t.rn = 1 and order_id = 101768
group by order_id;