Mysql 当存在聚合函数时，为什么要将其余列写入GROUP BY？
我有以下表格结构：Mysql 当存在聚合函数时，为什么要将其余列写入GROUP BY？,mysql,group-by,aggregate-functions,Mysql,Group By,Aggregate Functions,我有以下表格结构： // mytable +----+------+-------+-------------+ | id | type | score | unix_time | +----+------+-------+-------------+ | 1 | 1 | 5 | 1463508841 | | 2 | 1 | 10 | 1463508842 | | 3 | 2 | 5 | 1463508843 | | 4 | 1 |
// mytable
+----+------+-------+-------------+
| id | type | score | unix_time |
+----+------+-------+-------------+
| 1 | 1 | 5 | 1463508841 |
| 2 | 1 | 10 | 1463508842 |
| 3 | 2 | 5 | 1463508843 |
| 4 | 1 | 5 | 1463508844 |
| 5 | 2 | 15 | 1463508845 |
| 6 | 1 | 10 | 1463508846 |
+----+------+-------+-------------+
SELECT SUM(score), unix_time
FROM mytable
WHERE 1
GROUP BY type
+-------+-------------+
| score | unix_time |
+-------+-------------+
| 30 | 1463508841 |
| 20 | 1463508843 |
+-------+-------------+
unix\u timegroupbygroupby+-------+-------------+
| score | unix_time |
+-------+-------------+
| 30 | 1463508841 |
| 30 | 1463508842 |
| 20 | 1463508843 |
| 30 | 1463508844 |
| 20 | 1463508845 |
| 30 | 1463508846 |
+-------+-------------+
请有人给我解释清楚，
groupbySELECT type,
SUM(score) as sum_of_score,
MIN(unix_time) as start_unix_time,
MAX(unix_time) as end_unix_time
FROM mytable
WHERE 1
GROUP BY type
也许你需要这样的东西：
SELECT type,
SUM(score) as sum_of_score,
MIN(unix_time) as start_unix_time,
MAX(unix_time) as end_unix_time
FROM mytable
WHERE 1
GROUP BY type
在
groupbyunix\u timeunix\u time专业人士告诉你把它放在GROUPBY子句中的原因是为了让结果有意义！另一种方法是将
unix\u-timeGROUP BYunix\u-timeunix\u time专业人士告诉你把它放在GROUPBY子句中的原因是为了让结果有意义！另一种方法是将
unix\u time