SQL Server 2008 Spatial: find a point in polygon

If you cannot change the data-type for the stored polygons to GEOGRAPHY then you can convert the input latitude and longitude to GEOMETRY and use the STContains or STIntersects against the converted value.

DECLARE @PointGeography GEOGRAPHY = geography::Point(43.365267, -80.971974, 4326)
DECLARE @PointGeometry GEOMETRY = geometry::STGeomFromWKB(@PointGeography.STAsBinary(), 4326);

SELECT @PolygonGeometry.STContains(@PointGeometry);

Going the opposite direction -- trying to convert the GEOMETRY polygons to GEOGRPAHY -- is error-prone and likely to fail from my experience.

And note that if you try to create the GEOMETRY point directly from the latitude and longitude values then the STContains (or STIntersects) won't work (i.e. won't give a match when they should).

I think the geography method STIntersects() will do what you want:

DECLARE @g geography;
DECLARE @h geography;
SET @g = geography::STGeomFromText('POLYGON((-122.358 47.653, -122.348 47.649, -122.348 47.658, -122.358 47.658, -122.358 47.653))', 4326);
SET @h = geography::Point(47.653, -122.358, 4326)

SELECT @g.STIntersects(@h)

declare @g geometry
set @g=geometry::STGeomFromText('POLYGON((-33.229869 -70.891988, -33.251124 -70.476616, -33.703094 -70.508045, -33.693931 -70.891052,-33.229869 -70.891988))',0)

DECLARE @h geometry;

SET @h = geometry::STGeomFromText('POINT(-33.3906300 -70.5725020)', 0);
SELECT @g.STContains(@h);