我有一张名为travel的表格如下：
+-------+-----+----------+
| Name | Day | Distance |
+-------+-----+----------+
| Ravi | 1 | 10 |
| Ravi | 2 | 21 |
| Ravi | 3 | 23 |
| Hari | 1 | 12 |
| Hari | 2 | 32 |
| Kiran | 1 | 12 |
| Kiran | 2 | 32 |
| Kiran | 3 | 21 |
| Kiran | 4 | 43 |
+-------+-----+----------+
将sql中的group用作此表
select name, day, distance, sum(distance) as total_dist
from travel
group by name;
我得到的结果如下
+-------+-----+----------+------------+
| Name | Day | Distance | total_dist |
+-------+-----+----------+------------+
| Ravi | 1 | 10 | 54 |
| Hari | 1 | 12 | 44 |
| Kiran | 1 | 12 | 108 |
+-------+-----+----------+------------+
默认情况下，mysql为未聚合的列提供顶行。但我更希望获得聚合值的所有行或组中底行的行，如下所示：
+-------+-----+----------+------------+
| Name | Day | Distance | total_dist |
+-------+-----+----------+------------+
| Ravi | 3 | 23 | 54 |
| Hari | 2 | 32 | 44 |
| Kiran | 4 | 43 | 108 |
+-------+-----+----------+------------+
或以这种方式：
+-------+-----+----------+------------+
| Name | Day | Distance | total_dist |
+-------+-----+----------+------------+
| Ravi | 1 | 10 | 54 |
| Ravi | 2 | 21 | 54 |
| Ravi | 3 | 23 | 54 |
| Hari | 1 | 12 | 44 |
| Hari | 2 | 32 | 44 |
| Kiran | 1 | 12 | 108 |
| Kiran | 2 | 32 | 108 |
| Kiran | 3 | 21 | 108 |
| Kiran | 4 | 43 | 108 |
+-------+-----+----------+------------+
我是使用mysql的新手，并且在使用group by时感到困惑，如果以上两个结果中的任何一个都可以获得，请引导我。
答案 0 :(得分：0)
要为每个组获取包含sum的整个列表，您可以使用子查询并将join总回到原始表：
select t.name, t.day, t.distance, t2.total_dist
from travel t
join (select name, sum(distance) total_dist
from travel
group by name) t2 on t.name = t2.name
或者为了获得每个组的max天，只需在子查询中包含max(day)：
select t.name, t.day, t.distance, t2.total_dist
from travel t
join (select name, sum(distance) total_dist, max(day) max_day
from travel
group by name) t2 on t.name = t2.name and t.day = t2.max_day
答案 1 :(得分：0)
它适合你
select name,max(day),max(distance)
from tablename
group by name
和其他案例
select name,max(day),max(distance),(select sum(distance) from table) as total_dist
from tablename
group by name