STSrid (geography Data Type)
STSrid is an integer representing the spatial reference identifier (SRID) of the instance.
The first example creates a geography instance with the SRID value 4326 (WGS84) and uses STSrid to confirm the SRID.
DECLARE @g geography; SET @g = geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656)', 4326); SELECT @g.STSrid;
The second example uses STSrid to change the SRID value of the instance to 4267 (NAD27) and then confirms the modified SRID value.
SET @g.STSrid = 4267; SELECT @g.STSrid;