11.5.6 Functions That Test Spatial Relationships Between Geometries

The OpenGIS specification defines the following functions, which MySQL does not yet implement. They should appear in future releases. When implemented, they will provide full support for spatial analysis, not just MBR-based support.

The functions operate on two geometry values g1 and g2.

Contains(g1,g2)

Returns 1 or 0 to indicate whether or not g1 completely contains g2.

Crosses(g1,g2)

Returns 1 if g1 spatially crosses g2. Returns NULL if g1 is a Polygon or a MultiPolygon, or if g2 is a Point or a MultiPoint. Otherwise, returns 0. The term spatially crosses denotes a spatial relation between two given geometries that has the following properties:

• The two geometries intersect
• Their intersection results in a geometry that has a dimension that is one less than the maximum dimension of the two given geometries
• Their intersection is not equal to either of the two given geometries

Disjoint(g1,g2)

Returns 1 or 0 to indicate whether or not g1 is spatially disjoint from (does not intersect) g2.

Equals(g1,g2)

Returns 1 or 0 to indicate whether or not g1 is spatially equal to g2.

Intersects(g1,g2)

Returns 1 or 0 to indicate whether or not g1 spatially intersects g2.

Overlaps(g1,g2)

Returns 1 or 0 to indicate whether or not g1 spatially overlaps g2. The term spatially overlaps is used if two geometries intersect and their intersection results in a geometry of the same dimension but not equal to either of the given geometries.

Touches(g1,g2)

Returns 1 or 0 to indicate whether or not g1 spatially touches g2. Two geometries spatially touch if the interiors of the geometries do not intersect, but the boundary of one of the geometries intersects either the boundary or the interior of the other.

Within(g1,g2)

Returns 1 or 0 to indicate whether or not g1 is spatially within g2.

Distance(g1,g2)

Returns as a double-precision number the shortest distance between any two points in the two geometries.

Related(g1,g2,pattern_matrix)

Returns 1 or 0 to indicate whether or not the spatial relationship specified by pattern_matrix exists between g1 and g2. Returns -1 if the arguments are NULL. The pattern matrix is a string. Its specification will be noted here when this function is implemented.

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