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  • 10/01/2010

Point

In SQL Server spatial data, a Point is a 0-dimensional object representing a single location and may contain Z (elevation) and M (measure) values.

Geography Data Type

The Point type for geography data type represents a single location where x and y represent longitud and latitude values respectively. The values for longitud and latitude are measured in degrees. Values for longitud always lie in the interval (-180, 180] and values inputted outside this range are wrapped around to fit in this range. For example, if 190 is inputted for longitude then it will be wrapped to the value -170. Values for latitude always lie in the interval [-90, 90] and values that are inputted outside this range will throw an exception.

Examples

The following example creates a geometry Point instance representing the point (3, 4) with an SRID of 0.

DECLARE @g geometry;
SET @g = geometry::STGeomFromText('POINT (3 4)', 0);

The next example creates a geometryPoint instance representing the point (3, 4) with a Z (elevation) value of 7, an M (measure) value of 2.5, and the default SRID of 0.

DECLARE @g geometry;
SET @g = geometry::Parse('POINT(3 4 7 2.5)');

The final example returns the X, Y, Z, and M values for the geometryPoint instance.

SELECT @g.STX;
SELECT @g.STY;
SELECT @g.Z;
SELECT @g.M;

Z and M values may be explicitly specified as NULL, as shown in the following example.

DECLARE @g geometry;
SET @g = geometry::Parse('POINT(3 4 NULL NULL)');