获取地理多边形的 Lat Long 点的函数 SQL

Question

我创建了一个函数，用于 return MS-SQL 中多点地理字段中的一串点。我想知道是否有更好的方法来做到这一点？我想要的是向不使用 SQL 地理数据类型（他们使用 SQL Lite）的外部客户提供一个点列表作为 Lat/Long 坐标。

   Create FUNCTION [dbo].GetLatLongForPolygon
(
    @Perimeter  GEOGRAPHY
)
RETURNS Varchar(max)
AS
BEGIN

      declare @NumPoints as Int
  declare @OutputString as varchar(max)
  declare @latpoint as varchar(max)
    declare @longpoint as varchar(max)

 set @NumPoints = @Perimeter.STNumPoints()



 while @NumPoints >0
     begin
        set   @LatPoint = @Perimeter.STPointN(@NumPoints).Lat 
        set @longpoint = @Perimeter.STPointN(@NumPoints).Long 
        set @OutputString = concat (@OutputString, '(' , @latpoint, ',', @longpoint , '), ')
        set @NumPoints = @NumPoints -1
    End

RETURN left (@OutputString, len(@outputstring)-1)

    GO

Answer 1

是的。就在这里。我正在使用计数 table 来消除光标和标准习语来模拟 T-SQL.

中丢失的字符串连接聚合

declare @g geography = geography::STLineFromText('LINESTRING(20 20, 21 21, 22 22)', 4236);

with cte as (
    select @g.STPointN(n.Number) as [Point]
    from dbadmin.dbo.Numbers as n
    where n.Number <= @g.STNumPoints()
)
select stuff((
    select ', ' + concat('(', Point.Lat, ', ', Point.Long, ')')
    from cte
    for xml path('')
), 1, 2, '')

获取地理多边形的 Lat Long 点的函数 SQL

Function to get Lat Long points for geography polygon SQL

sql-server

sqlgeography