公交线路查询应用实例

--转自邹建 IF OBJECT_ID('T_Line') IS NOT NULL DROP TABLE T_Line GO CREATE TABLE T_Line ( ID nvarchar(10), --公交线路号 Station nvarchar(10), --站点名称 Orders int ) --行车方向(通过它反应每个站的上一个、下一个站) GO INSERT T_Line SELECT N'8路' ,N'站A',1 UNION ALL SELECT N'8路' ,N'站B',2 UNION ALL SELECT N'8路' ,N'站C',3 UNION ALL SELECT N'8路' ,N'站D',4 UNION ALL SELECT N'8路' ,N'站J',5 UNION ALL SELECT N'8路' ,N'站L',6 UNION ALL SELECT N'8路' ,N'站M',7 UNION ALL SELECT N'20路' ,N'站G',1 UNION ALL SELECT N'20路' ,N'站H',2 UNION ALL SELECT N'20路' ,N'站I',3 UNION ALL SELECT N'20路' ,N'站J',4 UNION ALL SELECT N'20路' ,N'站L',5 UNION ALL SELECT N'20路' ,N'站M',6 UNION ALL SELECT N'255路',N'站N',1 UNION ALL SELECT N'255路',N'站O',2 UNION ALL SELECT N'255路',N'站P',3 UNION ALL SELECT N'255路',N'站Q',4 UNION ALL SELECT N'255路',N'站J',5 UNION ALL SELECT N'255路',N'站D',6 UNION ALL SELECT N'255路',N'站E',7 UNION ALL SELECT N'255路',N'站F',8 GO --乘车线路查询存储过程 IF OBJECT_ID('p_qry') IS NOT NULL DROP PROC p_qry GO CREATE PROC p_qry @Station_Start nvarchar(10), --起始站名 @Station_Stop nvarchar(10) --终点站名 AS SET NOCOUNT ON DECLARE @l int SET @l=0 SELECT ID,Station, Line=CAST('('+RTRIM(ID)+': '+RTRIM(Station) as nvarchar(4000)), Orders=Orders, [Level]=@l INTO # FROM T_Line WHERE Station=@Station_Start WHILE @@ROWCOUNT>0 AND NOT EXISTS(SELECT * FROM # WHERE Station=@Station_Stop) BEGIN SET @l=@l+1 INSERT #(Line,ID,Station,Orders,[Level]) SELECT Line=a.Line +CASE WHEN a.ID=b.ID THEN N'->'+RTRIM(b.Station) ELSE N') ∝ ('+RTRIM(b.ID)+N': '+RTRIM(b.Station) END, b.ID, b.Station, b.Orders, @l FROM # a,T_Line b WHERE a.[Level]=@l-1 AND(a.Station=b.Station AND a.ID <>b.ID OR a.ID=b.ID AND(a.Orders=b.Orders+1 OR a.Orders=b.Orders-1)) AND LEN(a.Line) <4000 AND PATINDEX('%[ >]'+b.Station+'[-)]%',a.Line)=0 END SELECT N'起点站'=@Station_Start, N'终点站'=@Station_Stop , N'乘车线路'=Line+N')' FROM # WHERE [Level]=@l AND Station=@Station_Stop IF @@ROWCOUNT =0 --如果未有可以到达的线路,则显示处理结果表备查 SELECT * FROM # SET NOCOUNT OFF GO --调用 EXEC p_qry N'站A',N'站Q' /* 起点站 终点站 乘车线路 ---------- ---------- --------------------------------------------------------- 站A 站Q (8路: 站A->站B->站C->站D->站J) ∝ (255路: 站J->站Q) 站A 站Q (8路: 站A->站B->站C->站D) ∝ (255路: 站D->站J->站Q) */