Relate
RELATE(g1 Geometry, g2 Geometry, matrix string)
Alias: ST_RELATE
Result type: integer
Returns 1 if g1 and g2 relate in the way specified by matrix; returns 0 otherwise.
matrix is a string 9 characters long, each character specifies the desired dimension of the intersection between two objects.
The 9 sets of intersecting objects are:
The characters in the string are read left-to-right, top-to-bottom into the corresponding table. For example, the forth character corresponds to the second row in the first column (boundary of g1 and interior of g2).
If g1 and g2 are two diamonds:
The interior of g1 is (dimension 2):
The boundary of g1 is (dimension 1):
The exterior of g1 is (dimension 2):
So, the intersection of the boundary of g1 and interior of g2 is (dimension 1):
For each of the 9 tests, the desired dimension can be specified to be 0, 1, 2, * (any), F (empty), or T (non-empty).
Examples:
Are g1 and g2 disjoint? Use the matrix FF*FF****.
If g1 and g2 are disjoint:
• The interior of g1 does not intersect with the interior or boundary of g2 , it intersects completely with the exterior of g2 (FF*).
• The boundary of g1 does not intersect with the interior or boundary of g2 , it intersects completely with the exterior of g2 (FF*).
• The exterior of g1 intersects with the interior, boundary, and exterior of g2 (***).
g1 and g2 are disjoint:
SELECT RELATE(POLYFROMTEXT('POLYGON((0 0, 2 0, 2 2, 0 2, 0 0))'), POLYFROMTEXT('POLYGON((4 4, 4 6, 6 6, 6 4, 4 4))'), 'FF*FF****');
-------------
col1
-------------
1
-------------
g1 and g2 not are disjoint:
SELECT RELATE(POLYFROMTEXT('POLYGON((0 0, 4 0, 4 4, 0 4, 0 0))'), POLYFROMTEXT('POLYGON((2 2, 2 6, 6 6, 6 2, 2 2))'), 'FF*FF****');
-------------
col1
-------------
0
-------------
