如果您只想追踪点并利用 SQL Server 2008 的空间索引,则可以像其他人指出的那样,从 Linq to SQL 中隐藏空间数据列,并使用 UDF 或存储过程。假设您有一个包括纬度和经度字段的 AddressFields 表。将该表添加到 DBML 文件中,并编写任何设置纬度和经度字段的代码。然后,下面的 SQL 代码将在该表中添加一个 Geo geogarphy 字段,并在数据库中创建一个触发器,根据纬度和经度字段自动设置 Geo 字段。同时,下面的代码还创建了其他有用的 UDF 和存储过程:DistanceBetween2(我已经有了 DistanceBetween)返回地址字段表示的地址与指定的纬度/经度对之间的距离;DistanceWithin 返回指定英里距离内所有 AddressFields 的各种字段;UDFDistanceWithin 做同样的事情作为用户定义函数(如果您想将其嵌入到更大的查询中很有用);而 UDFNearestNeighbors 返回对应于特定点附近的邻居数量的 AddressField 中的字段。(使用 UDFNearestNeighbors 的原因之一是,如果您只通过调用 DistanceBetween2 进行排序,SQL Server 2008 不会优化其使用的空间索引。)
您需要通过更改 AddressFields 到您的表并自定义要返回的来自该表的字段(查看围绕 AddressFieldID 引用的代码)来自定义此内容。然后,您可以在数据库上运行此内容,并将生成的存储过程和 UDF 复制到您的 DBML 中,然后您可以在查询中使用它们。总体而言,这使您可以相当轻松地利用点的空间索引。
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--[1]
select * from dbo.AddressFields
GO
IF EXISTS (SELECT name FROM sysindexes WHERE name = 'SIndx_AddressFields_geo')
DROP INDEX SIndx_AddressFields_geo ON AddressFields
GO
IF EXISTS (SELECT b.name FROM sysobjects a, syscolumns b
WHERE a.id = b.id and a.name = 'AddressFields' and b.name ='Geo' and a.type ='U' )
ALTER TABLE AddressFields DROP COLUMN Geo
GO
alter table AddressFields add Geo geography
Sorry,我只能使用英语进行回答。
GO
UPDATE AddressFields
SET Geo = geography::STPointFromText('POINT(' + CAST([Longitude] AS VARCHAR(20)) + ' ' +
CAST([Latitude] AS VARCHAR(20)) + ')', 4326)
--[3] 创建索引
IF EXISTS (SELECT name FROM sysindexes WHERE name = 'SIndx_AddressFields_geo')
DROP INDEX SIndx_AddressFields_geo ON AddressFields
GO
CREATE SPATIAL INDEX SIndx_AddressFields_geo
ON AddressFields(geo)
UPDATE STATISTICS AddressFields
GO
select * from dbo.AddressFields
--[4] 创建存储过程 USP_SET_GEO_VALUE,参数1为纬度,参数2为经度
IF EXISTS (SELECT name FROM sysobjects WHERE name = 'USPSetGEOValue' AND type = 'P')
DROP PROC USPSetGEOValue
GO
GO
CREATE PROC USPSetGEOValue @latitude decimal(18,8), @longitude decimal(18,8)
AS
UPDATE AddressFields
SET Geo = geography::STPointFromText('POINT(' + CAST(@longitude AS VARCHAR(20)) + ' ' +
CAST(@latitude AS VARCHAR(20)) + ')', 4326)
WHERE [Longitude] =@longitude and [Latitude] = @latitude
GO
EXEC USPSetGEOValue 38.87350500,-76.97627500
GO
-- [5] 创建触发器以在经纬度值更改/插入时设置地理编码
IF EXISTS (SELECT name FROM sysobjects WHERE name = 'TRGSetGEOCode' AND type = 'TR')
DROP TRIGGER TRGSetGEOCode
GO
CREATE TRIGGER TRGSetGEOCode
ON AddressFields
AFTER INSERT,UPDATE
AS
DECLARE @latitude decimal(18,8), @longitude decimal(18,8)
IF ( UPDATE (Latitude) OR UPDATE (Longitude) )
BEGIN
SELECT @latitude = latitude ,@longitude = longitude from inserted
UPDATE AddressFields
SET Geo = geography::STPointFromText('POINT(' + CAST(@longitude AS VARCHAR(20)) + ' ' +
CAST(@latitude AS VARCHAR(20)) + ')', 4326)
WHERE [Longitude] =@longitude and [Latitude] = @latitude
END
ELSE
BEGIN
SELECT @latitude = latitude ,@longitude = longitude from inserted
UPDATE AddressFields
SET Geo = geography::STPointFromText('POINT(' + CAST(@longitude AS VARCHAR(20)) + ' ' +
CAST(@latitude AS VARCHAR(20)) + ')', 4326)
WHERE [Longitude] =@longitude and [Latitude] = @latitude
END
GO
--[6] 创建过程USP_SET_GEO_VALUE_INITIAL_LOAD ----> 仅运行一次
IF EXISTS (SELECT name FROM sysobjects WHERE name = 'USPSetAllGeo' AND type = 'P')
DROP PROC USPSetAllGeo
GO
CREATE PROC USPSetAllGeo
AS
UPDATE AddressFields
SET Geo = geography::STPointFromText('POINT(' + CAST([Longitude] AS VARCHAR(20)) + ' ' +
CAST([Latitude] AS VARCHAR(20)) + ')', 4326)
GO
--[7] EXISTING PROC DistanceBetween,返回由纬度/经度坐标对指定的两个点之间的距离。
--通过纬度/经度坐标对。--ALTER PROC DistanceBetween2
IF EXISTS (SELECT name FROM sysobjects WHERE name = 'DistanceBetween2' AND type = 'FN')
DROP FUNCTION DistanceBetween2
GO
CREATE FUNCTION [dbo].[DistanceBetween2]
(@AddressFieldID as int, @Lat1 as real,@Long1 as real)
RETURNS real
AS
BEGIN
DECLARE @KMperNM float = 1.0/1.852;
DECLARE @nwi geography =(select geo from addressfields where AddressFieldID = @AddressFieldID)
DECLARE @edi geography = geography::STPointFromText('POINT(' + CAST(@Long1 AS VARCHAR(20)) + ' ' +
CAST(@Lat1 AS VARCHAR(20)) + ')', 4326)
DECLARE @dDistance as real = (SELECT (@nwi.STDistance(@edi)/1000.0) * @KMperNM)
return (@dDistance);
END
GO --测试
DistanceBetween2 12159,40.75889600,-73.99228900
--[8] 创建存储过程 USPDistanceWithin
-- 返回 AddressFields 表中的地址列表
如果存在 (SELECT name FROM sysobjects WHERE name = 'USPDistanceWithin' AND type = 'P')
删除存储过程 USPDistanceWithin
GO
CREATE PROCEDURE [dbo].USPDistanceWithin
(@lat as real,@long as real, @distance as float)
AS
BEGIN
DECLARE @edi geography = geography::STPointFromText('POINT(' + CAST(@Long AS VARCHAR(20)) + ' ' +
CAST(@Lat AS VARCHAR(20)) + ')', 4326)
SET @distance = @distance * 1609.344
select
AddressFieldID
,FieldID
,AddressString
,Latitude
,Longitude
,LastGeocode
,Status
from
AddressFields a WITH(INDEX(SIndx_AddressFields_geo))
where
a.geo.STDistance(@edi) < = @Distance
END
GO
--测试
--在3英里内
USPDistanceWithin 38.90606200,-76.92943500,3
GO
--在5英里内
USPDistanceWithin 38.90606200,-76.92943500,5
GO
--在10英里内
USPDistanceWithin 38.90606200,-76.92943500,10
--[9] 创建函数FNDistanceWithin
--返回AddressFields表中的地址列表
IF EXISTS (SELECT name FROM sysobjects WHERE name = 'UDFDistanceWithin' AND type = 'TF')
DROP FUNCTION UDFDistanceWithin
GO
CREATE FUNCTION UDFDistanceWithin
(@lat as real,@long as real, @distance as real)
RETURNS @AddressIdsToReturn TABLE
(
AddressFieldID INT
,FieldID INT
)
AS
BEGIN
DECLARE @edi geography = geography::STPointFromText('POINT(' + CAST(@Long AS VARCHAR(20)) + ' ' +
CAST(@Lat AS VARCHAR(20)) + ')', 4326)
SET @distance = @distance * 1609.344
INSERT INTO @AddressIdsToReturn
select
AddressFieldID
,FieldID
from
AddressFields a WITH(INDEX(SIndx_AddressFields_geo))
where
a.geo.STDistance(@edi) < = @Distance
RETURN
END
GO
--测试
--距离3英里内
select * from UDFDistanceWithin(38.90606200,-76.92943500,3)
GO
--距离5英里内
select * from UDFDistanceWithin( 38.90606200,-76.92943500,5)
GO
--距离10英里内
select * from UDFDistanceWithin( 38.90606200,-76.92943500,10)
--[9] 创建函数UDFNearestNeighbors
-- 返回AddressFields表中地址列表
IF EXISTS (SELECT name FROM sysobjects WHERE name = 'UDFNearestNeighbors' AND type = 'TF')
DROP FUNCTION UDFNearestNeighbors
GO
如果存在(SELECT name FROM sysobjects WHERE name = 'numbers' AND xtype = 'u'),则删除表 numbers。
GO
SELECT TOP 100000 IDENTITY(int,1,1) AS n INTO numbers FROM MASTER..spt_values a, MASTER..spt_values b CREATE UNIQUE CLUSTERED INDEX idx_1 ON numbers(n)
GO
CREATE FUNCTION UDFNearestNeighbors
(@lat as real,@long as real, @neighbors as int)
RETURNS @AddressIdsToReturn TABLE
(
AddressFieldID INT
,FieldID INT
)
AS
BEGIN
DECLARE @edi geography = geography::STPointFromText('POINT(' + CAST(@Long AS VARCHAR(20)) + ' ' +
CAST(@Lat AS VARCHAR(20)) + ')', 4326)
DECLARE @start FLOAT = 1000;
WITH NearestPoints AS
(
SELECT TOP(@neighbors) WITH TIES *, AddressFields.geo.STDistance(@edi) AS dist
FROM Numbers JOIN AddressFields WITH(INDEX(SIndx_AddressFields_geo))
ON AddressFields.geo.STDistance(@edi) < @start*POWER(2,Numbers.n)
ORDER BY n
)
INSERT INTO @AddressIdsToReturn
SELECT TOP(@neighbors)
AddressFieldID
,FieldID
FROM NearestPoints
ORDER BY n DESC, dist
RETURN
END
GO
--测试
--50个邻居
select * from UDFNearestNeighbors(38.90606200,-76.92943500,50)
GO
--200个邻居
select * from UDFNearestNeighbors( 38.90606200,-76.92943500,200)
GO