Tests if a geometry value is spatially contained within another geometry value.
SELECT NEW ST_Point( 1, 1 ) .ST_Within( NEW ST_Polygon( 'Polygon(( 0 0, 2 0, 1 2, 0 0 ))' ) )
The following example tests if a line is within a polygon. The line is completely within the polygon, but the interior of the line and the interior of the polygon do not intersect (the line only intersects the polygon on the polygon's boundary, and the boundary is not part of the interior), so the example returns 0. If ST_CoveredBy was used in place of ST_Within, ST_CoveredBy would return 1.
SELECT NEW ST_LineString( 'LineString( 0 0, 1 0 )' ) .ST_Within( NEW ST_Polygon( 'Polygon(( 0 0, 2 0, 1 2, 0 0 ))' ) )
The following example lists the ShapeIDs where the given point is within the Shape geometry. This example returns the result 3,5. Note that ShapeID 6 is not listed because the point intersects that row's Shape polygon at the polygon's boundary.
SELECT LIST( ShapeID ORDER BY ShapeID ) FROM SpatialShapes WHERE NEW ST_Point( 1, 4 ).ST_Within( Shape ) = 1
SQL/MM (ISO/IEC 13249-3: 2006) 5.1.30