Question

我是使用Geography数据类型的新手，但我已经想出如何使用它从一个点获取一个zipcodes列表（在存储过程中我只是将点作为varchar而我提供了它“经度纬度”）这样很棒。

然而，我需要展示的下一件事就是距离这一点大约几英里。我看了几个答案，找不到任何答案。

这是我的存储过程：

ALTER PROCEDURE [dbo].[GetZipCodesByDistance]
@point varchar(500),
@distance int
AS
BEGIN
SET NOCOUNT ON;

declare @geoPoint geography
set @geoPoint = geography::STGeomFromText('POINT (' + @point + ')', 4326)
                           .STBuffer(@distance / 0.0006213712)
SELECT   zc.zip_id AS ZipId
        ,zc.zip_code AS ZipCodeId
        ,zc.zip_type AS ZipType
        ,zc.zip_city AS ZipCity
        ,zc.zip_utc AS ZipUtc
        ,zc.zip_dst AS ZipDst
        ,zc.zip_latitude AS ZipLatitude
        ,zc.zip_longitude AS ZipLongitude,
        (Geo.MakeValid()).STDistance(@geoPoint)
FROM zip_code zc
WHERE zc.Geo.STIntersects(@geoPoint) = 1

所以，我的问题是......如何让它从这一点返回里程？我试图添加列“（Geo.MakeValid（））。STDistance（@geoPoint）”但它返回全零。

感谢您的帮助！

AJ

Answer 1

试试这个

SELECT geography::STGeomFromText('POINT(' + zc.zip_latitude
                                    + ' ' + zc.zip_longitude + ')'
                                 , 4326).STDistance(@geoPoint);

Answer 2

我仍然不明白你的要求究竟是什么。我们有类似的要求来查找邮政编码之间的距离。查看执行工作的示例函数

CREATE FUNCTION Wrk.ZipDistance
(
    @Zip1 VARCHAR(20)
    ,@Zip2 VARCHAR(20)
)
RETURNS FLOAT
AS
BEGIN
    DECLARE @LatLong1 GEOGRAPHY
    DECLARE @LatLong2 GEOGRAPHY
    DECLARE @Result FLOAT
    SELECT
        @LatLong1 = LatLong
    FROM
        PostalCode
    WHERE
        PostalCode = @Zip1

    SELECT
        @LatLong2 = LatLong
    FROM
        PostalCode
    WHERE
        PostalCode = @Zip2

    SELECT @Result = @Lat1.STDistance(@Lat2) 

    RETURN @Result/1000
END

希望这有帮助

Answer 3

我建议引入一个单独的变量来保存点与缓冲区域的对比：

ALTER PROCEDURE [dbo].[GetZipCodesByDistance]
@point varchar(500),
@distance int
AS
BEGIN
SET NOCOUNT ON;

declare @geoPoint geography
set @geoPoint = geography::STGeomFromText('POINT (' + @point + ')', 4326);

declare @searchArea geography
set @searchArea = @geoPoint.STBuffer(@distance / 0.0006213712)

select  zc.zip_id AS ZipId
        ,zc.zip_code AS ZipCodeId
        ,zc.zip_type AS ZipType
        ,zc.zip_city AS ZipCity
        ,zc.zip_utc AS ZipUtc
        ,zc.zip_dst AS ZipDst
        ,zc.zip_latitude AS ZipLatitude
        ,zc.zip_longitude AS ZipLongitude,
        (Geo.MakeValid()).STDistance(@geoPoint)
        FROM zip_code zc
where zc.Geo.STIntersects(@searchArea) = 1

我尝试添加列＆＃34;（Geo.MakeValid（））。STDistance（@geoPoint）＆＃34;但它返回全零。

之前您正在计算找到的点与搜索区域之间的距离 - 当然我们已经建立（通过STIntersects）他们＆＃39 ;在该地区内。所以我改变了一些事情，以便STDistance调用使用的是点而不是区域。

（当然，我还建议，如果可能的话，更改存储过程的参数，以便您传递已经构造的geography而不是字符串。但是这可能并不总是可能的）

Answer 4

好吧，想办法让这项工作成功。

存储过程如下所示：

ALTER PROCEDURE [dbo].[GetZipCodesByDistance] @point VARCHAR(500),
@distance INT
AS
BEGIN
SET NOCOUNT ON;
DECLARE @geoPoint GEOGRAPHY
SET @geoPoint = GEOGRAPHY::STGeomFromText('POINT (' + @point + ')', 4326);

DECLARE @searchArea GEOGRAPHY
SET @searchArea = @geoPoint.STBuffer(@distance / 0.0006213712)

DECLARE @ZipDistance TABLE(
ZipCode VARCHAR(5),
ZipLatitude DECIMAL(9,6),
ZipLongitude DECIMAL(9,6),
Distance DECIMAL(9,2)
)

INSERT INTO @ZipDistance
SELECT
        zc.zip_code AS ZipCode
        ,zc.zip_latitude AS ZipLatitude
        ,zc.zip_longitude AS ZipLongitude
        ,CAST((((Geo.MakeValid()).STDistance(@geoPoint))/1609.34) AS DECIMAL(9,2)) AS Distance
FROM zip_code zc
WHERE zc.Geo.STIntersects(@searchArea) = 1

SELECT * FROM @ZipDistance
END

然后我创建了一个模型：

public class ZipCodeWithDistance
{
    public string ZipCode { get; set; }
    public decimal ZipLatitude { get; set; }
    public decimal ZipLongitude { get; set; }
    public decimal Distance { get; set; }
}

在DbContext中，我有以下内容：

public List<ZipCodeWithDistance> GetZipCodes(string point, int distance)
{
    var zipCodes = this.Database.SqlQuery<ZipCodeWithDistance>(
    "GetZipCodesByDistance @point, @distance",
    new SqlParameter("point", point),
    new SqlParameter("distance", distance)
    ).ToList();

    return zipCodes;
}

在FacilityModel中，我有：

[NotMapped]
public decimal Distance { get; set; }

最后，在服务中，我有以下内容：

public IQueryable<Facility>GetFacilitiesByZipCodes(List<ZipCodeWithDistance> zipCodes)
{
    var zipCodeName = zipCodes.Select(x => x.ZipCode).ToList();
    var facilities = oandpDbContext.Facilities.Where(x => zipCodeName.Contains(x.ZipCode.Substring(0, 5))).ToList();
    facilities.ForEach(x =>
    {
        var zip = zipCodes.FirstOrDefault(y => y.ZipCode == x.ZipCode.Substring(0, 5));
        if (zip != null)
        {
            x.Distance = zip.Distance;
        }
    });
return facilities.AsQueryable();
}

不确定它是否是完成此操作的最佳/最有效方式，但它确实有效。欢迎任何想法或意见！谢谢，AJ

从地理存储过程中获取里程数

4 个答案: