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    CheckRadii: Identifying Tight Radius Curves sections within LineString geometry data
    Generating random point data for SQL Server 2008 Spatial
    New Presentation on Active (Searchable) Spatial Metadata for SQL Server 2008 Spatial and FreeText
    STisGeo: Checking if a column in a table or a view is of type geometry or geography
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    STMBR2Geometry/STMBR2Geography functions
    Extracting geometry types from geometry/geography objects in SQL Server 2008
    Getting the number of coordinate dimensions of a geometry/geography object in SQL Server 2008
    STDumpPoints: A Function that Dumps the Vertices/Points in a geometry
    toGeography and toGeography Conversion Functions for SQL Server 2008 Spatial
    Write text file with spatial data from SQL Server 2008
    Loading Shapefiles into Geography type column in SQL Server 2008
    Tip #6: Correcting invalid geometries
    Tip #5: Where or where has my little column gone
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All Blog Articles, Data Models and Free Source Code by Simon Greener, The SpatialDB Advisor is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

toGeography and toGeography Conversion Functions for SQL Server 2008 Spatial

Monday September 28 2009 at 05:13

KeywordsConvert geometry geography STToGeometry STToGeography
Summary

ToGeometry and ToGeography conversion functions.

I have been doing some SQL Server 2008 programming lately and have come across the fact that TSQL does not allowing a programmer to create overloaded functions.

This is an issue, when programming SQL Server 2008 Spatial, because of use of its implementation of two different data types for geodetic and projected data: geography and geometry.

Thus, if I want to create a function like “DumpPoints”: I have to implement it twice (as is done with the CLR functions in SQL Spatial Tools ) eg:

  1. CREATE FUNCTION STDumpPointsGeom( @p_geom geometry )
  2. etc
  3. --
  4. CREATE FUNCTION STDumpPointsGeog( @p_geom geography )
  5. etc

Or I can implement it once – STDumpPoints( @p_geom geometry) – and call it using the following conversion functions.

  1. USE [GISDB]  -- Change this to your database
  2. GO
  3. --
  4. CREATE FUNCTION [dbo].[STToGeography](@p_geom geometry,
  5.                                       @p_srid INT = NULL)
  6.  RETURNS geography
  7. AS
  8. BEGIN
  9.   RETURN geography::STGeomFromText(@p_geom.AsTextZM(),
  10.          CASE WHEN @p_srid IS NULL
  11.               THEN @p_geom.STSrid
  12.               ELSE @p_srid
  13.           END );
  14. END
  15. GO
  16. --
  17. CREATE FUNCTION [dbo].[STToGeometry](@p_geog geography,
  18.                                      @p_srid INT = NULL)
  19.  RETURNS geometry
  20. AS
  21. BEGIN
  22.   RETURN geometry::STGeomFromText(@p_geog.AsTextZM(),
  23.          CASE WHEN @p_srid IS NULL
  24.               THEN @p_geog.STSrid
  25.               ELSE @p_srid
  26.           END );
  27. END
  28. GO

Testing its we get:

  1. SELECT [dbo].[STDensify] (
  2.          [dbo].[STToGeometry] (
  3.             geography::STGeomFromText('LINESTRING(-10 0,-5 5,10 10)',4326),
  4.       NULL),
  5.      2.1,3,2).AsTextZM();
  6. GO
  7. dGeom
  8. LINESTRING (-10 0, -8.75 1.25, -7.5 2.5, -6.25 3.75, -5 5, -3.125 5.625, -1.25 6.25, 0.625 6.875, 2.5 7.5, 4.375 8.125, 6.25 8.75, 8.125 9.375, 10 10)
  9. --
  10. SELECT dbo.STToGeography(
  11.            dbo.STToGeometry(
  12.                geography::STGeomFromText('LINESTRING(147.234 -43.2345, 148.234 -43.2345)',4326),
  13.                0),
  14.            4326).STAsText()
  15.        AS geog;

geog
LINESTRING (147.234 -43.2345, 148.234 -43.2345)

Not all that clever, but I find them useful. I hope you might too.

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Comment [1]

Me gustaría conocer opciones de como puedo generar un Geojson de mis poligonos en base de datos definidos como tipo geography

— Esperanza Najera Valente · 27 February 2019, 04:43 · #