Question

我有一个包含此信息的数据库：

trip1 => stop1
trip1 => stop15
trip1 => stop20

trip2 => stop8
trip2 => stop11
trip2 => stop17

trip3 => stop15
trip3 => stop11
trip3 => stop25

如果用户想要从stop1转到stop17，我会打印此信息：

stop1 (trip1) => stop15 (trip3) => stop11 (trip2) => stop17

是否可以通过sql请求获取对应的stop15和stop11？我是通过使用pl sql来做的。

Answer 1

你需要这里的最短路径算法，如@Eng。 Samer T写道。
一个天真的查询为这个样本数据生成所有可能的路径，从stop1到stop17提供了8个可能的路径，而你指向的路径是最短路径。
看看这个例子：http://sqlfiddle.com/#!4/7742c/13

随着更多的数据，这个天真的查询可能永远不会完成，因为一些可能的路径可能是无穷无尽的。

SELECT "Path"
FROM (

select trip,
       pidstop,
       CONNECT_BY_ROOT trip as root_pid,
       CONNECT_BY_ROOT pidstop As root_pidstop,
    SYS_CONNECT_BY_PATH(pidstop||' ('||trip||') ', 
                         '/') As "Path"
from table1
start with pidstop = 'stop1'
connect by nocycle 
      prior pidstop = pidstop
      and prior trip <> trip
      or 
      prior trip = trip
      and prior pidstop <> pidstop
)
WHERE root_pidstop = 'stop1'
  AND pidstop = 'stop17'



/stop1 (trip1) /stop15 (trip1) /stop15 (trip3) /stop11 (trip3) /stop11 (trip2) /stop8 (trip2) /stop17 (trip2)  
/stop1 (trip1) /stop15 (trip1) /stop15 (trip3) /stop11 (trip3) /stop11 (trip2) /stop17 (trip2)  
/stop1 (trip1) /stop15 (trip1) /stop15 (trip3) /stop25 (trip3) /stop11 (trip3) /stop11 (trip2) /stop8 (trip2) /stop17 (trip2)  
/stop1 (trip1) /stop15 (trip1) /stop15 (trip3) /stop25 (trip3) /stop11 (trip3) /stop11 (trip2) /stop17 (trip2)  
/stop1 (trip1) /stop20 (trip1) /stop15 (trip1) /stop15 (trip3) /stop11 (trip3) /stop11 (trip2) /stop8 (trip2) /stop17 (trip2)  
/stop1 (trip1) /stop20 (trip1) /stop15 (trip1) /stop15 (trip3) /stop11 (trip3) /stop11 (trip2) /stop17 (trip2)  
/stop1 (trip1) /stop20 (trip1) /stop15 (trip1) /stop15 (trip3) /stop25 (trip3) /stop11 (trip3) /stop11 (trip2) /stop8 (trip2) /stop17 (trip2)  
/stop1 (trip1) /stop20 (trip1) /stop15 (trip1) /stop15 (trip3) /stop25 (trip3) /stop11 (trip3) /stop11 (trip2) /stop17 (trip2)

检索轨迹的对应关系

1 个答案: