ST_Disjoint

Definition

ST_Disjoint takes two ST_Geometries and returns 1 (Oracle) or t (PostgreSQL) if the intersection of two geometries produces an empty set; otherwise, it returns 0 (Oracle) or f (PostgreSQL).

Syntax

sde.st_disjoint (g1 sde.st_geometry, g2 sde.st_geometry)

Return type

Boolean

Example

This example creates two tables, sensitive_areas and hazardous_sites, and inserts values into each.

CREATE TABLE sensitive_areas (id integer, 
                               zones sde.st_geometry); 

CREATE TABLE hazardous_sites (id integer, 
                              loc sde.st_geometry); 

INSERT INTO sensitive_areas VALUES (
1,
sde.st_geometry ('polygon ((20 30, 30 30, 30 40, 20 40, 20 30))', 0)
);

INSERT INTO sensitive_areas VALUES (
2,
sde.st_geometry ('polygon ((30 30, 30 50, 50 50, 50 30, 30 30))', 0)
);

INSERT INTO sensitive_areas VALUES (
3,
sde.st_geometry ('polygon ((40 40, 40 60, 60 60, 60 40, 40 40))', 0)
);

INSERT INTO hazardous_sites VALUES (
4,
sde.st_geometry ('point (60 60)', 0)
);

INSERT INTO hazardous_sites VALUES (
5,
sde.st_geometry ('point (30 30)', 0)
);

The SELECT statement lists the names of all sensitive areas that are outside the buffer of a hazardous waste site.

Oracle

SELECT sa.id
FROM SENSITIVE_AREAS sa, HAZARDOUS_SITES hs
WHERE sde.st_disjoint ((sde.st_buffer (hs.loc, .1)), sa.zones) = 1
AND hs.id = 5;

ID

3

PostgreSQL

SELECT sa.id
FROM sensitive_areas sa, hazardous_sites hs
WHERE sde.st_disjoint ((sde.st_buffer (hs.loc, .1)), sa.zones) = 't'
AND hs.id = 5;

id

3

Tip:

You could use the ST_Intersects function instead in this query by equating the result of the function to 0, because ST_Intersects and ST_Disjoint return opposite results. The ST_Intersects function uses the spatial index when evaluating the query, whereas the ST_Disjoint function does not.