糟糕的MySQL LEFT JOIN性能，逐组最大化

糟糕的MySQL LEFT JOIN性能，逐组最大化

这应该给出相同的结果，并且性能要好得多。

SELECt  p1.*FROM    prod_prices p1        INNER JOIN        (   SELECt  ID, MAX(Date) AS Date FROM    prod_prices GROUP BY ID        ) AS p2 ON p1.ID = p2.ID  AND p1.Date = p2.Date