MySQL查询比较，选择字段IN对INNER JOIN

Question

下午好。

我有两个不同的查询执行完全相同的指令。但令我惊讶的是，我认为效率更高的那个比另一个更好，我一直试图理解这一点，但遗憾的是无法做到，有人能帮助我理解为什么吗？

提前非常感谢你。

原作（我认为会表现不佳）：

SELECT *, competitions.name AS nome
FROM   competitions 
 INNER JOIN areas ON areas.area_id = competitions.area_id
 INNER JOIN seasons ON competitions.competition_id = seasons.competition_id 
WHERE  seasons.id IN (SELECT MAX(seasons.id)
                      FROM   seasons
                      GROUP  BY seasons.competition_id)

第二个（生成filesort并使用临时）

SELECT *, competitions.name as nome, MAX(seasons.id)
FROM   seasons
 INNER JOIN competitions ON competitions.competition_id = seasons.competition_id
 INNER JOIN areas ON areas.area_id = competitions.area_id
GROUP  BY seasons.competition_id