Question

table1，如下所示

+-------------------------+--------+--------+--------+----------+---------+---------+
|          time           |  regno |  radar |  speed |  heading |  people |  lights |
+-------------------------+--------+--------+--------+----------+---------+---------+
| 2017/03/28 06:00:06.112 |     11 |   1100 |     50 |  down    |       4 |  false  |
| 2017/03/28 06:00:06.112 |     12 |   1111 |     40 |  up      |       1 |  false  |
| 2017/03/28 06:00:06.113 |     11 |   1100 |     50 |  down    |       4 |  false  |
| 2017/03/28 06:00:07.100 |     21 |   1100 |     60 |  down    |       4 |  false  |
+-------------------------+--------+--------+--------+----------+---------+---------+

我需要生成一个输出表，其中捕获来自table1的选择字段的聚合值，如下所示。

+-----------+-------+------+------+---------+
| attribute |  avg  |  min |  max |  median |
+-----------+-------+------+------+---------+
| speed     |    50 |   40 |   60 |      40 |
| people    |  3.25 |    1 |    4 |       4 |
+-----------+-------+------+------+---------+

我可以在临时表中单独聚合每个属性，然后对临时表进行联合以获得上面的输出，但是当有大量属性（在我的情况下大约是20）时它会变得难以处理 - 是否存在更聪明的方式来解决这个问题？

Answer 1

你可以通过联合查询来完成这个，试试这个

SELECT avg(speed),min(speed),max(speed),'speed' as speed FROM `table1`
UNION 
SELECT avg(people),min(people),max(people),'people' as people FROM `table1`

聚合表的选择字段

1 个答案: