我有下表:
路线历史
+----+-----------------+-----------------+---------------+-----------------+--------------+
| id |departure | arrival |terminal_ori_id| terminal_dest_id|next_route_id |
+----+-----------------+-----------------+---------------+-----------------+--------------+
| 8 |2020-05-01 12:00 |2020-05-01 17:00 |5 | 1 | [null] |
| 9 |2020-05-01 08:00 |2020-05-01 10:00 |4 | 5 | 8 |
| 10 |2020-05-01 03:00 |2020-05-01 07:00 |3 | 4 | 9 |
+----+---------------------+-----------------+---------------+-----------------+--------------+
我想以某种格式打印起飞和到达时间,航站楼的名称以及航班的磅数。例如,航班10的规模可扩展至航班9,而航班9的规模可扩展至航班8。因此,航班10具有2个标度,航班9具有1个标度。有办法吗?
这是查询的内容:
SELECT h.id,
to_char(h.departure, 'Mon DD YYYY HH:12:MI AM') departure,
to_char(h.arrival, 'Mon DD YYYY HH:12:MI AM') arrival,
t.name as terminal_origin,
td.name as terminal_destiny,
FROM history_of_routes h
JOIN terminals t ON t.id = h.terminal_ori_id
JOIN terminals td ON td.id = h.terminal_dest_id;
我只是缺少刻度部分,我不知道该怎么做。
A recursive CTE将完成工作:
WITH RECURSIVE cte AS (
SELECT id, 0 AS scale, next_route_id
FROM history_of_routes h
UNION ALL
SELECT c.id, c.scale + 1, h.next_route_id
FROM cte c
JOIN history_of_routes h ON h.id = c.next_route_id
WHERE c.next_route_id IS NOT NULL -- end of path
)
SELECT id, scale
FROM cte
WHERE next_route_id IS NULL;
结果:
root_id |规模------:| ----:8 | 09 | 1个10 | 2
db <>小提琴here
假设next_route_id IS NULL
终止每个飞行路径。集成:
WITH RECURSIVE cte AS (
SELECT id, 0 AS scale, next_route_id
FROM history_of_routes h
UNION ALL
SELECT c.id, c.scale + 1, h.next_route_id
FROM cte c
JOIN history_of_routes h ON h.id = c.next_route_id
WHERE c.next_route_id IS NOT NULL -- end of path
)
SELECT c.id
, c.scale
, to_char(h.departure, 'Mon DD YYYY HH:12:MI AM') AS departure
, to_char(h.arrival , 'Mon DD YYYY HH:12:MI AM') AS arrival
, o.name AS terminal_origin
, d.name AS terminal_destiny
FROM cte c
JOIN history_of_routes h USING (id)
JOIN terminals o ON o.id = h.terminal_ori_id
JOIN terminals d ON d.id = h.terminal_dest_id
WHERE c.next_route_id IS NULL;