mysql - 获取mysql行的最新日期

Question

抱歉我的描述不好，但我正在尝试获取最后吃每种水果的每个人的最新日期。我认为我的分组不正确，或者我完全错过了一些东西。有人可以帮我弄这个吗？提前致谢。

T1
+--------+--------+--------+
| person | fruit  |  date  |
+--------+--------+--------+
|  Bob   | apple  | 1-1-13 |
|  Bob   | apple  | 1-4-13 |
|  Bob   | apple  | 1-6-13 |
|  Bob   | orange | 1-2-13 |
|  John  | apple  | 1-3-13 |
|  John  | orange | 1-2-13 |
|  John  | orange | 1-4-13 |
|  John  | orange | 1-9-13 |
+--------+--------+--------+

Results I'm looking for
+--------+--------+--------+
| person | fruit  |  date  |
+--------+--------+--------+
|  Bob   | apple  | 1-6-13 |
|  Bob   | orange | 1-2-13 |
|  John  | apple  | 1-3-13 |
|  John  | orange | 1-9-13 |
+--------+--------+--------+

我从阅读类似帖子中得到的尝试。

SELECT * FROM T1 
  JOIN (
    SELECT person,max(date) AS latest 
      FROM T1 GROUP BY person
    ) T2
  ON T1.person = T2.person AND T1.date = T2.latest

Resulting in
+--------+--------+--------+
| person | fruit  |  date  |
+--------+--------+--------+
|  Bob   | apple  | 1-6-13 |
|  John  | orange | 1-9-13 |
+--------+--------+--------+

我如何让它也分离水果柱？

Answer 1

这里不需要JOIN。带有 . 的简单聚合GROUP BY。

SELECT person, fruit, DATE_FORMAT(MAX(date), '%c-%e-%y') AS max_date
FROM T1
GROUP BY person, fruit

结果

| 人 | 水果 | MAX_DATE |
------------------------------
| 鲍勃 | 苹果| 高分辨率照片| CLIPARTO 1-6-13 |
| 鲍勃 | 橙色 | 1-2-13 |
| 约翰 | 苹果| 高分辨率照片| CLIPARTO 1-3-13 |
| 约翰 | 橙色 | 1-9-13 |

看到它在行动