Spatial Data

Introduction#

There are 2 spatial data types

Geometry X/Y coordinate system for a flat surface

Geography Latitude/Longitude coordinate system for a curved surface (the earth). There are multiple projections of curved surfaces so each geography spatial must let SQL Server know which projection to use. The usual Spatial Reference ID (SRID) is 4326, which is measuring distances in Kilometers. This is the default SRID used in most web maps

POINT

Creates a single Point. This will be a geometry or geography point depending on the class used.

Parameter	Detail
Lat or X	Is a float expression representing the x-coordinate of the Point being generated
Long or Y	Is a float expression representing the y-coordinate of the Point being generated
String	Well Known Text (WKB) of a geometry/geography shape
Binary	Well Known Binary (WKB) of a geometry/geography shape
SRID	Is an int expression representing the spatial reference ID (SRID) of the geometry/geography instance you wish to return

--Explicit constructor 
DECLARE @gm1 GEOMETRY = GEOMETRY::Point(10,5,0)

DECLARE @gg1 GEOGRAPHY = GEOGRAPHY::Point(51.511601,-0.096600,4326)

--Implicit constructor (using WKT - Well Known Text)
DECLARE @gm1 GEOMETRY = GEOMETRY::STGeomFromText('POINT(5 10)', 0)

DECLARE @gg1 GEOGRAPHY= GEOGRAPHY::STGeomFromText('POINT(-0.096600 51.511601)', 4326)

--Implicit constructor (using WKB - Well Known Binary)
DECLARE @gm1 GEOMETRY = GEOMETRY::STGeomFromWKB(0x010100000000000000000014400000000000002440, 0)

DECLARE @gg1 GEOGRAPHY= GEOGRAPHY::STGeomFromWKB(0x01010000005F29CB10C7BAB8BFEACC3D247CC14940, 4326)