Question

我有一张这样的表：

+-------------------------------+---------------+---------------------+
| color                         | code          | date                |
+-------------------------------+---------------+---------------------+
| red                           |           300 | 2017-06-23 11:44:14 |
| red                           |           600 | 2017-06-23 11:37:14 |
| green                         |           200 | 2017-06-23 09:08:59 |
| green                         |           200 | 2017-06-23 09:06:59 |
| yellow                        |             0 | 2017-06-21 09:23:43 |
| blue                          |           100 | 2017-06-21 09:13:36 |
| blue                          |           105 | 2017-06-21 09:12:36 |
| red                           |           200 | 2017-06-21 09:11:05 |
| green                         |           200 | 2017-06-21 09:09:46 |
| yellow                        |           900 | 2017-06-21 09:01:04 |
| blue                          |           400 | 2017-06-21 08:50:50 |
| blue                          |           400 | 2017-06-21 08:50:30 |
| red                           |           700 | 2017-06-21 08:49:52 |
| red                           |           800 | 2017-06-21 08:49:03 |
| green                         |           500 | 2017-06-20 20:15:29 |
| yellow                        |           200 | 2017-06-20 19:31:47 |
| blue                          |           300 | 2017-06-20 19:15:02 |
| blue                          |           300 | 2017-06-19 19:20:02 |
+-------------------------------+---------------+---------------------+

我需要一个查询，它会创建一个表格，显示颜色列中每种颜色的总量，并显示每种颜色的最新代码和日期。

我到目前为止最接近的是这个查询：

SELECT color, 
max(code) AS code, 
max(date) AS date, 
count(*) AS count 
FROM checks 
GROUP BY color 
ORDER BY count DESC LIMIT 12;

这几乎是完美的，除了代码列显示最高编号而不是最新代码。所以黄色代码应该是900，因为它应该是0，因为0是最新的。

上述查询的示例表：

     +---------------------------+---------------+---------------------+-------+
    | color                     | code          | date                | count |
    +---------------------------+---------------+---------------------+-------+
    | blue                      |           400 | 2017-06-21 09:13:36 |     6 |
    | red                       |           800 | 2017-06-23 11:44:14 |     5 |
    | green                     |           500 | 2017-06-23 09:08:59 |     4 |
    | yellow                    |           900 | 2017-06-21 09:23:43 |     3 |
    +---------------------------+---------------+---------------------+-------+

如果我将max(code)更改为code，则会获得第一个代码，因此黄色代码将为200.

我需要结果表看起来像这样：

+---------------------------+---------------+---------------------+-------+
| color                     | code          | date                | count |
+---------------------------+---------------+---------------------+-------+
| blue                      |           100 | 2017-06-21 09:13:36 |     6 |
| red                       |           300 | 2017-06-23 11:44:14 |     5 |
| green                     |           200 | 2017-06-23 09:08:59 |     4 |
| yellow                    |             0 | 2017-06-21 09:23:43 |     3 |
+---------------------------+---------------+---------------------+-------+

谢谢：）

Answer 1

这样的事情：

select t.*, the_table.code  from the_table
inner join
(select color, count(*), max(date) as maxdate from the_table group by color)t
on the_table.color = t.color and the_table.date = t.maxdate

mysql：从最新列获取数据

1 个答案: