The longitude property of the geography instance.
.Long
SQL Server type: float
CLR type: SqlDouble
In the OpenGIS model, Long is defined only on geography instances composed of a single point. This property will return NULL if geography instances contain more than a single point. This property is precise and read-only.
This example creates a Point instance and retrieves the longitude of the point.
DECLARE @g geography;
SET @g = geography::STGeomFromText('POINT(-122.34900 47.65100)', 4326);
SELECT @g.Long;