选择每个公交车站的最短时间

Question

我有一个包含time_id，bus_id，stop_id和time列的表。像这样：

time_id |bus_id     | stop_id     | time
1       |19         | 51          | 00:08:00
2       |19         | 51          | 00:09:00
3       |19         | 51          | 00:10:00
4       |19         | 12          | 00:08:30
5       |19         | 12          | 00:09:30
6       |19         | 12          | 00:10:30
7       |23         | 31          | 00:08:00
8       |23         | 31          | 00:09:00
9       |23         | 31          | 00:10:00
10      |23         | 42          | 00:08:30
11      |23         | 42          | 00:09:30
12      |23         | 42          | 00:10:30

我想要每组（bus_id和stop_id）的min（时间）行。像这样：

time_id |bus_id | stop_id     | time
1       |19     | 51          | 00:08:00
4       |19     | 12          | 00:08:30
7       |23     | 31          | 00:08:00
10      |23     | 42          | 00:08:30

任何帮助都会很棒。使用SQLite。

Answer 1

执行此操作的标准SQL是：

SELECT bus_id, stop_id, MIN(time) as time
FROM tablename
GROUP BY bus_id, stop_id
ORDER BY bus_id, stop_id

这将返回总线和停止ID的每个组合的时间字段的最小值。我还使用ORDER BY子句对结果进行了排序。