最快的求每个分组最后一个记录的方法
The fastest way to get the last record/last time record of each group in SQL:
For example:
SELECT B.*
FROM (
SELECT id_field, MAX(time_field) AS "time_field"
FROM a_table
GROUP BY id_field
) A
LEFT JOIN a_table B
ON A.time_field = B.time_field AND A.id_field = B.id_field