FROM: http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=77262
-- delete previous map
exec dbo.uspdijkstrainitializemap
-- create a new map
exec dbo.uspdijkstraaddpath 'a', 'b', 4
exec dbo.uspdijkstraaddpath 'a', 'd', 1
exec dbo.uspdijkstraaddpath 'b', 'a', 74
exec dbo.uspdijkstraaddpath 'b', 'c', 2
exec dbo.uspdijkstraaddpath 'b', 'e', 12
exec dbo.uspdijkstraaddpath 'c', 'b', 12
exec dbo.uspdijkstraaddpath 'c', 'f', 74
exec dbo.uspdijkstraaddpath 'c', 'j', 12
exec dbo.uspdijkstraaddpath 'd', 'e', 32
exec dbo.uspdijkstraaddpath 'd', 'g', 22
exec dbo.uspdijkstraaddpath 'e', 'd', 66
exec dbo.uspdijkstraaddpath 'e', 'f', 76
exec dbo.uspdijkstraaddpath 'e', 'h', 33
exec dbo.uspdijkstraaddpath 'f', 'i', 11
exec dbo.uspdijkstraaddpath 'f', 'j', 21
exec dbo.uspdijkstraaddpath 'g', 'd', 12
exec dbo.uspdijkstraaddpath 'g', 'h', 10
exec dbo.uspdijkstraaddpath 'h', 'g', 2
exec dbo.uspdijkstraaddpath 'h', 'i', 72
exec dbo.uspdijkstraaddpath 'i', 'f', 31
exec dbo.uspdijkstraaddpath 'i', 'j', 7
exec dbo.uspdijkstraaddpath 'i', 'h', 18
exec dbo.uspdijkstraaddpath 'j', 'f', 8
-- resolve route
exec dbo.uspdijkstraresolve 'a', 'i'
This is the output
From To Cost
---- -- ----
a b 4
b c 6
c j 18
j f 26
f i 37
CREATE TABLE [dbo].[Nodes] (
[NodeID] [int] IDENTITY (1, 1) NOT NULL ,
[NodeName] [varchar] (20) COLLATE Finnish_Swedish_CI_AS NOT NULL ,
[Cost] [int] NULL ,
[PathID] [int] NULL ,
[Calculated] [tinyint] NOT NULL
) ON [PRIMARY]
GO
CREATE TABLE [dbo].[Paths] (
[PathID] [int] IDENTITY (1, 1) NOT NULL ,
[FromNodeID] [int] NOT NULL ,
[ToNodeID] [int] NOT NULL ,
[Cost] [int] NOT NULL
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[Nodes] WITH NOCHECK ADD
CONSTRAINT [PK_Nodes] PRIMARY KEY CLUSTERED
(
[NodeID]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[Paths] WITH NOCHECK ADD
CONSTRAINT [PK_Paths] PRIMARY KEY CLUSTERED
(
[PathID]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[Paths] ADD
CONSTRAINT [FK_Paths_FromNodes] FOREIGN KEY
(
[FromNodeID]
) REFERENCES [dbo].[Nodes] (
[NodeID]
),
CONSTRAINT [FK_Paths_ToNodes] FOREIGN KEY
(
[ToNodeID]
) REFERENCES [dbo].[Nodes] (
[NodeID]
)
GO
CREATE PROCEDURE dbo.uspDijkstraInitializeMap
AS
DELETE
FROM Paths
DBCC CHECKIDENT (Paths, RESEED, 0)
DELETE
FROM Nodes
DBCC CHECKIDENT (Nodes, RESEED, 0)
GO
CREATE PROCEDURE dbo.uspDijkstraClearMap
AS
UPDATE Nodes
SET PathID = NULL,
Cost = NULL,
Calculated = 0
GO
CREATE PROCEDURE dbo.uspDijkstraAddPath
(
@FromNodeName VARCHAR(20),
@ToNodeName VARCHAR(20),
@Cost INT
)
AS
SET NOCOUNT ON
DECLARE @FromNodeID INT,
@ToNodeID INT,
@PathID INT
SELECT @FromNodeID = NodeID
FROM Nodes
WHERE NodeName = @FromNodeName
IF @FromNodeID IS NULL
BEGIN
INSERT Nodes
(
NodeName,
Calculated
)
VALUES (
@FromNodeName,
0
)
SELECT @FromNodeID = SCOPE_IDENTITY()
END
SELECT @ToNodeID = NodeID
FROM Nodes
WHERE NodeName = @ToNodeName
IF @ToNodeID IS NULL
BEGIN
INSERT Nodes
(
NodeName,
Calculated
)
VALUES (
@ToNodeName,
0
)
SELECT @ToNodeID = SCOPE_IDENTITY()
END
SELECT @PathID = PathID
FROM Paths
WHERE FromNodeID = @FromNodeID
AND ToNodeID = @ToNodeID
IF @PathID IS NULL
INSERT Paths
(
FromNodeID,
ToNodeID,
Cost
)
VALUES (
@FromNodeID,
@ToNodeID,
@Cost
)
ELSE
UPDATE Paths
SET Cost = @Cost
WHERE FromNodeID = @FromNodeID
AND ToNodeID = @ToNodeID
GO
CREATE PROCEDURE dbo.uspDijkstraResolve
(
@FromNodeName VARCHAR(20),
@ToNodeName VARCHAR(20)
)
AS
SET NOCOUNT ON
EXEC dbo.uspDijkstraClearMap
DECLARE @FromNodeID INT,
@ToNodeID INT,
@NodeID INT,
@Cost INT,
@PathID INT
SELECT @FromNodeID = NodeID,
@NodeID = NodeID
FROM Nodes
WHERE NodeName = @FromNodeName
IF @FromNodeID IS NULL
BEGIN
SELECT @FromNodeName = ISNULL(@FromNodeName, '')
RAISERROR ('From node name ''%s'' can not be found.', 16, 1, @FromNodeName)
RETURN
END
SELECT @ToNodeID = NodeID
FROM Nodes
WHERE NodeName = @ToNodeName
IF @ToNodeID IS NULL
BEGIN
SELECT @ToNodeName = ISNULL(@ToNodeName, '')
RAISERROR ('To node name ''%s'' can not be found.', 16, 1, @ToNodeName)
RETURN
END
UPDATE Nodes
SET Cost = 0
WHERE NodeID = @FromNodeID
WHILE @NodeID IS NOT NULL
BEGIN
UPDATE ToNodes
SET ToNodes.Cost = CASE
WHEN ToNodes.Cost IS NULL THEN FromNodes.Cost + Paths.Cost
WHEN FromNodes.Cost + Paths.Cost < ToNodes.Cost THEN FromNodes.Cost + Paths.Cost
ELSE ToNodes.Cost
END,
ToNodes.PathID = Paths.PathID
FROM Nodes AS FromNodes
INNER JOIN Paths ON Paths.FromNodeID = FromNodes.NodeID
INNER JOIN Nodes AS ToNodes ON ToNodes.NodeID = Paths.ToNodeID
WHERE FromNodes.NodeID = @NodeID
AND (ToNodes.Cost IS NULL OR FromNodes.Cost + Paths.Cost < ToNodes.Cost)
AND ToNodes.Calculated = 0
UPDATE FromNodes
SET FromNodes.Calculated = 1
FROM Nodes AS FromNodes
WHERE FromNodes.NodeID = @NodeID
SELECT @NodeID = NULL
SELECT TOP 1 @NodeID = Nodes.NodeID
FROM Nodes
WHERE Nodes.Calculated = 0
AND Nodes.Cost IS NOT NULL
ORDER BY Nodes.Cost
END
CREATE TABLE #Map
(
RowID INT IDENTITY(-1, -1),
FromNodeName VARCHAR(20),
ToNodeName VARCHAR(20),
Cost INT
)
IF EXISTS (SELECT NULL FROM Nodes WHERE NodeID = @ToNodeID AND Cost IS NULL)
BEGIN
SELECT FromNodeName,
ToNodeName,
Cost
FROM #Map
DROP TABLE #Map
RETURN
END
WHILE @FromNodeID <> @ToNodeID
BEGIN
SELECT @FromNodeName = FromNodes.NodeName,
@ToNodeName = ToNodes.NodeName,
@Cost = ToNodes.Cost,
@PathID = ToNodes.PathID
FROM Nodes AS ToNodes
INNER JOIN Paths ON Paths.PathID = ToNodes.PathID
INNER JOIN Nodes AS FromNodes ON FromNodes.NodeID = Paths.FromNodeID
WHERE ToNodes.NodeID = @ToNodeID
INSERT #Map
(
FromNodeName,
ToNodeName,
Cost
)
VALUES (
@FromNodeName,
@ToNodeName,
@Cost
)
SELECT @ToNodeID = Paths.FromNodeID
FROM Paths
WHERE Paths.PathID = @PathID
END
SELECT FromNodeName,
ToNodeName,
Cost
FROM #Map
ORDER BY RowID
DROP TABLE #Map
GO
在线图示例：http://www.dgp.toronto.edu/people/JamesStewart/270/9798s/Laffra/DijkstraApplet.html