®Geovin Du Dream Park™
----------------------------------------------------------------------- Road System道路
---------------------------------------------------------------------
-- Listing 9-3: DDL & Sample Data for Cities, Roads
SET NOCOUNT ON;
USE tempdb;
GO
IF OBJECT_ID('dbo.Roads') IS NOT NULL
DROP TABLE dbo.Roads;
GO
IF OBJECT_ID('dbo.Cities') IS NOT NULL
DROP TABLE dbo.Cities;
GO
CREATE TABLE dbo.Cities
(
cityidCHAR(3) NOT NULL PRIMARY KEY,
city VARCHAR(30) NOT NULL,
regionVARCHAR(30) NULL,
country VARCHAR(30) NOT NULL
);
INSERT INTO dbo.Cities(cityid, city, region, country)
VALUES('ATL', 'Atlanta', 'GA', 'USA');
INSERT INTO dbo.Cities(cityid, city, region, country)
VALUES('ORD', 'Chicago', 'IL', 'USA');
INSERT INTO dbo.Cities(cityid, city, region, country)
VALUES('DEN', 'Denver', 'CO', 'USA');
INSERT INTO dbo.Cities(cityid, city, region, country)
VALUES('IAH', 'Houston', 'TX', 'USA');
INSERT INTO dbo.Cities(cityid, city, region, country)
VALUES('MCI', 'Kansas City', 'KS', 'USA');
INSERT INTO dbo.Cities(cityid, city, region, country)
VALUES('LAX', 'Los Angeles', 'CA', 'USA');
INSERT INTO dbo.Cities(cityid, city, region, country)
VALUES('MIA', 'Miami', 'FL', 'USA');
INSERT INTO dbo.Cities(cityid, city, region, country)
VALUES('MSP', 'Minneapolis', 'MN', 'USA');
INSERT INTO dbo.Cities(cityid, city, region, country)
VALUES('JFK', 'New York', 'NY', 'USA');
INSERT INTO dbo.Cities(cityid, city, region, country)
VALUES('SEA', 'Seattle', 'WA', 'USA');
INSERT INTO dbo.Cities(cityid, city, region, country)
VALUES('SFO', 'San Francisco', 'CA', 'USA');
INSERT INTO dbo.Cities(cityid, city, region, country)
VALUES('ANC', 'Anchorage', 'AK', 'USA');
INSERT INTO dbo.Cities(cityid, city, region, country)
VALUES('FAI', 'Fairbanks', 'AK', 'USA');
CREATE TABLE dbo.Roads
(
city1 CHAR(3) NOT NULL REFERENCES dbo.Cities,
city2 CHAR(3) NOT NULL REFERENCES dbo.Cities,
distance INT NOT NULL,
PRIMARY KEY(city1, city2),
CHECK(city1 < city2),
CHECK(distance > 0)
);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('ANC', 'FAI', 359);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('ATL', 'ORD', 715);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('ATL', 'IAH', 800);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('ATL', 'MCI', 805);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('ATL', 'MIA', 665);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('ATL', 'JFK', 865);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('DEN', 'IAH', 1120);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('DEN', 'MCI', 600);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('DEN', 'LAX', 1025);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('DEN', 'MSP', 915);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('DEN', 'SEA', 1335);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('DEN', 'SFO', 1270);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('IAH', 'MCI', 795);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('IAH', 'LAX', 1550);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('IAH', 'MIA', 1190);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('JFK', 'ORD', 795);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('LAX', 'SFO', 385);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('MCI', 'ORD', 525);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('MCI', 'MSP', 440);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('MSP', 'ORD', 410);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('MSP', 'SEA', 2015);
INSERT INTO dbo.Roads(city1, city2, distance) VALUES('SEA', 'SFO', 815);
GO
SELECT * FROM dbo.Roads
GO
WITH Roads2--每对城市生成行
AS
(
SELECT city1 AS from_city,city2 AS to_city FROM dbo.Roads
UNION ALL
SELECT city2,city2 FROM dbo.Roads
),
RoadPaths AS
(
--返回第一级别的所有可到达的城市对
SELECT from_city,to_city,
CAST('.'+from_city+'.'+to_city+'.' AS VARCHAR(max)) AS path
FROM Roads2
UNION ALL
SELECT F.from_city,T.to_city,--返回下一级别的可到达的城市对
CAST(F.path+T.to_city+'.' AS VARCHAR(MAX)) --路径需要验明循环
FROM RoadPaths AS F
JOIN Roads2 AS T
ON CASE WHEN F.path LIKE '%.'+T.to_city+'.%' --如果to_city出现在from_city的路径中，则检测到循环
THEN 1 ELSE 0 END =0
AND F.to_city =T.from_city
)
SELECT DISTINCT from_city,to_city FROM RoadPaths;--返回Roads 的传递包
GO
---------------------------------------------------------------------
-- Undirected Cyclic Graph
---------------------------------------------------------------------
-- Listing 9-38: Transitive Closure of Roads (Undirected Cyclic Graph) 传递闭包
WITH Roads2 -- Two rows for each pair (f-->t, t-->f)
AS
(
SELECT city1 AS from_city, city2 AS to_city FROM dbo.Roads
UNION ALL
SELECT city2, city1 FROM dbo.Roads
),
RoadPaths AS
(
-- Return all first-level reachability pairs
SELECT from_city, to_city,
-- path is needed to>
CAST('.' + from_city + '.' + to_city + '.' AS VARCHAR(MAX)) AS path
FROM Roads2
UNION ALL
-- Return next-level reachability pairs
SELECT F.from_city, T.to_city,
CAST(F.path + T.to_city + '.' AS VARCHAR(MAX))
FROM RoadPaths AS F
JOIN Roads2 AS T
-- if to_city appears in from_city's path, cycle detected
ON CASE WHEN F.path LIKE '%.' + T.to_city + '.%'
THEN 1 ELSE 0 END = 0
AND F.to_city = T.from_city
)
-- Return Transitive Closure of Roads
SELECT DISTINCT from_city, to_city
FROM RoadPaths;
GO
-- Listing 9-39: Creation Script for the fn_RoadsTC UDF
IF OBJECT_ID('dbo.fn_RoadsTC') IS NOT NULL
DROP FUNCTION dbo.fn_RoadsTC;
GO
CREATE FUNCTION dbo.fn_RoadsTC() RETURNS @RoadsTC TABLE (
from_city VARCHAR(3) NOT NULL,
to_city VARCHAR(3) NOT NULL,
PRIMARY KEY (from_city, to_city)
)
AS
BEGIN
DECLARE @added as INT;
INSERT INTO @RoadsTC(from_city, to_city)
SELECT city1, city2 FROM dbo.Roads;
SET @added = @@rowcount;
INSERT INTO @RoadsTC
SELECT city2, city1 FROM dbo.Roads
SET @added = @added + @@rowcount;
WHILE @added > 0 BEGIN
INSERT INTO @RoadsTC
SELECT DISTINCT TC.from_city, R.city2
FROM @RoadsTC AS TC
JOIN dbo.Roads AS R
ON R.city1 = TC.to_city
WHERE NOT EXISTS
(SELECT * FROM @RoadsTC AS TC2
WHERE TC2.from_city = TC.from_city
AND TC2.to_city = R.city2)
AND TC.from_city <> R.city2;
SET @added = @@rowcount;
INSERT INTO @RoadsTC
SELECT DISTINCT TC.from_city, R.city1
FROM @RoadsTC AS TC
JOIN dbo.Roads AS R
ON R.city2 = TC.to_city
WHERE NOT EXISTS
(SELECT * FROM @RoadsTC AS TC2
WHERE TC2.from_city = TC.from_city
AND TC2.to_city = R.city1)
AND TC.from_city <> R.city1;
SET @added = @added + @@rowcount;
END
RETURN;
END
GO
-- Use the fn_RoadsTC UDF--传递闭包函数
SELECT * FROM dbo.fn_RoadsTC();
GO
-- Listing 9-40: All paths and distances in Roads (15262 rows）返回所有路径和距离
WITH Roads2
AS
(
SELECT city1 AS from_city, city2 AS to_city, distance FROM dbo.Roads
UNION ALL
SELECT city2, city1, distance FROM dbo.Roads
),
RoadPaths AS
(
SELECT from_city, to_city, distance,
CAST('.' + from_city + '.' + to_city + '.' AS VARCHAR(MAX)) AS path
FROM Roads2
UNION ALL
SELECT F.from_city, T.to_city, F.distance + T.distance,
CAST(F.path + T.to_city + '.' AS VARCHAR(MAX))
FROM RoadPaths AS F
JOIN Roads2 AS T
ON CASE WHEN F.path LIKE '%.' + T.to_city + '.%'
THEN 1 ELSE 0 END = 0
AND F.to_city = T.from_city
)
-- Return all paths and distances
SELECT * FROM RoadPaths;
GO
-- Listing 9-41: Shortest paths in Roads 返回最短路径
WITH Roads2
AS
(
SELECT city1 AS from_city, city2 AS to_city, distance FROM dbo.Roads
UNION ALL
SELECT city2, city1, distance FROM dbo.Roads
),
RoadPaths AS
(
SELECT from_city, to_city, distance,
CAST('.' + from_city + '.' + to_city + '.' AS VARCHAR(MAX)) AS path
FROM Roads2
UNION ALL
SELECT F.from_city, T.to_city, F.distance + T.distance,
CAST(F.path + T.to_city + '.' AS VARCHAR(MAX))
FROM RoadPaths AS F
JOIN Roads2 AS T
ON CASE WHEN F.path LIKE '%.' + T.to_city + '.%'
THEN 1 ELSE 0 END = 0
AND F.to_city = T.from_city
),
RoadsMinDist -- Min distance for each pair in TC 每对城市的最短距离
AS
(
SELECT from_city, to_city, MIN(distance) AS mindist
FROM RoadPaths
GROUP BY from_city, to_city
)
-- Return shortest paths and distances 返回最短路径和距离
SELECT RP.*
FROM RoadsMinDist AS RMD
JOIN RoadPaths AS RP
ON RMD.from_city = RP.from_city
AND RMD.to_city = RP.to_city
AND RMD.mindist = RP.distance;
GO
-- Listing 9-42: Load Shortest Road Paths Into a Table 把最短路径保存到表
WITH Roads2
AS
(
SELECT city1 AS from_city, city2 AS to_city, distance FROM dbo.Roads
UNION ALL
SELECT city2, city1, distance FROM dbo.Roads
),
RoadPaths AS
(
SELECT from_city, to_city, distance,
CAST('.' + from_city + '.' + to_city + '.' AS VARCHAR(MAX)) AS path
FROM Roads2
UNION ALL
SELECT F.from_city, T.to_city, F.distance + T.distance,
CAST(F.path + T.to_city + '.' AS VARCHAR(MAX))
FROM RoadPaths AS F
JOIN Roads2 AS T
ON CASE WHEN F.path LIKE '%.' + T.to_city + '.%'
THEN 1 ELSE 0 END = 0
AND F.to_city = T.from_city
),
RoadsMinDist
AS
(
SELECT from_city, to_city, MIN(distance) AS mindist
FROM RoadPaths
GROUP BY from_city, to_city
)
SELECT RP.*
INTO dbo.RoadPaths
FROM RoadsMinDist AS RMD
JOIN RoadPaths AS RP
ON RMD.from_city = RP.from_city
AND RMD.to_city = RP.to_city
AND RMD.mindist = RP.distance;
CREATE UNIQUE CLUSTERED INDEX>
ON dbo.RoadPaths(from_city, to_city);
GO
-- Return shortest path between Los Angeles and New York 测试查询最短路径
SELECT * FROM dbo.RoadPaths
WHERE from_city = 'LAX' AND to_city = 'JFK';
GO
-- Listing 9-43: Creation Script for the fn_RoadsTC UDF
IF OBJECT_ID('dbo.fn_RoadsTC') IS NOT NULL
DROP FUNCTION dbo.fn_RoadsTC;
GO
CREATE FUNCTION dbo.fn_RoadsTC() RETURNS @RoadsTC TABLE
(
uniquifier INT NOT NULL>
from_cityVARCHAR(3) NOT NULL,
to_city VARCHAR(3) NOT NULL,
distance INT NOT NULL,
route VARCHAR(MAX) NOT NULL,
PRIMARY KEY (from_city, to_city, uniquifier)
)
AS
BEGIN
DECLARE @added AS INT;
INSERT INTO @RoadsTC
SELECT city1 AS from_city, city2 AS to_city, distance,
'.' + city1 + '.' + city2 + '.'
FROM dbo.Roads;
SET @added = @@rowcount;
INSERT INTO @RoadsTC
SELECT city2, city1, distance, '.' + city2 + '.' + city1 + '.'
FROM dbo.Roads;
SET @added = @added + @@rowcount;
WHILE @added > 0 BEGIN
INSERT INTO @RoadsTC
SELECT DISTINCT TC.from_city, R.city2,
TC.distance + R.distance, TC.route + city2 + '.'
FROM @RoadsTC AS TC
JOIN dbo.Roads AS R
ON R.city1 = TC.to_city
WHERE NOT EXISTS
(SELECT * FROM @RoadsTC AS TC2
WHERE TC2.from_city = TC.from_city
AND TC2.to_city = R.city2
AND TC2.distance <= TC.distance + R.distance)
AND TC.from_city <> R.city2;
SET @added = @@rowcount;
INSERT INTO @RoadsTC
SELECT DISTINCT TC.from_city, R.city1,
TC.distance + R.distance, TC.route + city1 + '.'
FROM @RoadsTC AS TC
JOIN dbo.Roads AS R
ON R.city2 = TC.to_city
WHERE NOT EXISTS
(SELECT * FROM @RoadsTC AS TC2
WHERE TC2.from_city = TC.from_city
AND TC2.to_city = R.city1
AND TC2.distance <= TC.distance + R.distance)
AND TC.from_city <> R.city1;
SET @added = @added + @@rowcount;
END
RETURN;
END
GO
-- Return shortest paths and distances
SELECT from_city, to_city, distance, route
FROM (SELECT from_city, to_city, distance, route,
RANK() OVER (PARTITION BY from_city, to_city
ORDER BY distance) AS rk
FROM dbo.fn_RoadsTC()) AS RTC
WHERE rk = 1;
GO
-- Cleanup
DROP TABLE dbo.RoadPaths;
GO
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