public void TestSTDistance()
        {
            using (var db = new PostGisTestDataConnection(TestDatabaseConnectionString))
            {
                var point = new NTSGS.Point(new NTSGS.Coordinate(-72.1235, 42.3521))
                {
                    SRID = SRID4326
                };
                db.Insert(new TestGeometryEntity(1, point));

                var lineString = new NTSGS.LineString(new[] { new NTSGS.Coordinate(-72.1260, 42.45), new NTSGS.Coordinate(-72.123, 42.1546) })
                {
                    SRID = SRID4326
                };
                db.Insert(new TestGeometryEntity(2, lineString));

                // Geometry example - units in planar degrees 4326 is WGS 84 long lat, units are degrees.
                var distances4326 = db.TestGeometries
                                    .Select(g => g.Geometry.STDistance(point))
                                    .ToList();

                Assert.AreEqual(2, distances4326.Count);
                Assert.AreEqual(0.0, distances4326[0]);
                Assert.AreEqual(0.00150567726382822, distances4326[1].Value, 1.0E-9);

                // Geometry example - units in meters (SRID:3857, proportional to pixels on popular web maps).
                var distances3857 = db.TestGeometries
                                    .Select(g => g.Geometry.STTransform(SRID3857).STDistance(point.STTransform(SRID3857)))
                                    .ToList();

                Assert.AreEqual(2, distances3857.Count);
                Assert.AreEqual(0.0, distances3857[0]);
                Assert.AreEqual(167.441410065196, distances3857[1].Value, 1.0E-9);

                var nullDistance = db.TestGeometries
                                   .Where(g => g.Id == 1)
                                   .Select(g => g.Geometry.STDistance(null))
                                   .Single();
                Assert.IsNull(nullDistance);

                Assert.AreEqual(
                    0.00150567726382282,
                    db.Select(() => MeasurementFunctions.STDistance(
                                  "SRID=4326;POINT(-72.1235 42.3521)",
                                  "SRID=4326;LINESTRING(-72.1260 42.45, -72.123 42.1546)")).Value,
                    1.0E-12);

                Assert.IsNull(db.Select(() => MeasurementFunctions.STDistance((NTSG)null, (NTSG)null)));

                // geography
                var pointGeography = new NTSGS.Point(-72.1235, 42.3521)
                {
                    SRID = SRID4326
                };
                db.Insert(new TestGeographyEntity(1, pointGeography));

                var lineGeography = new NTSGS.LineString(new[] { new NTSGS.Coordinate(-72.1260, 42.45), new NTSGS.Coordinate(-72.123, 42.1546) })
                {
                    SRID = SRID4326
                };
                db.Insert(new TestGeographyEntity(2, lineGeography));

                var distance1 = db.TestGeographies
                                .Where(g => g.Id == 1)
                                .Select(g => g.Geography.STDistance(db.TestGeographies.Where(g0 => g0.Id == 2).Single().Geography))
                                .Single();

                Assert.AreEqual(123.802077, distance1.Value, 1.0E-6);

                var distance2 = db.TestGeographies
                                .Where(g => g.Id == 1)
                                .Select(g => g.Geography.STDistance(db.TestGeographies.Where(g0 => g0.Id == 2).Single().Geography, false))
                                .Single();

                Assert.AreEqual(123.475737, distance2.Value, 1.0E-6);
            }
        }
        public void TestSTDistance()
        {
            using (var db = new PostGisTestDataConnection(TestDatabaseConnectionString))
            {
                var point = new NTSG.Point(new NTSG.Coordinate(-72.1235, 42.3521))
                {
                    SRID = SRID4326
                };
                db.Insert(new TestGeometryEntity(1, point));
                var lineString = new NTSG.LineString(new[] { new NTSG.Coordinate(-72.1260, 42.45), new NTSG.Coordinate(-72.123, 42.1546) })
                {
                    SRID = SRID4326
                };
                db.Insert(new TestGeometryEntity(2, lineString));

                // Geometry example - units in planar degrees 4326 is WGS 84 long lat, units are degrees.
                var distances4326 = db.TestGeometries.Select(g => g.Geometry.STDistance(point)).ToList();

                Assert.AreEqual(2, distances4326.Count);
                Assert.AreEqual(0.0, distances4326[0]);
                Assert.AreEqual(0.00150567726382822, distances4326[1], 1.0E9);

                // Geometry example - units in meters (SRID:3857, proportional to pixels on popular web maps).
                var distances3857 = db.TestGeometries.Select(g => g.Geometry.STTransform(SRID3857).STDistance(point.STTransform(SRID3857))).ToList();

                Assert.AreEqual(2, distances3857.Count);
                Assert.AreEqual(0.0, distances3857[0]);
                Assert.AreEqual(167.441410065196, distances3857[1], 1.0E9);

                var nullDistance = db.TestGeometries.Where(g => g.Id == 1).Select(g => g.Geometry.STDistance(null)).Single();
                Assert.IsNull(nullDistance);
            }
        }