PostGIS 1.5.8 Manual - Fedora Project Packages GIT repositories

PostGIS 1.5.8 Manual103 / 310NoteSQL-MM defines the result of ST_IsEmpty(NULL) to be 0, while PostGIS returns NULL.This method implements the OpenGIS Simple Features Implementation Specification for SQL 1.1. s2.1.1.1This method implements the SQL/MM specification. SQL-MM 3: 5.1.7This method supports Circular Strings and CurvesExamplesSELECT ST_IsEmpty(’GEOMETRYCOLLECTION(EMPTY)’);st_isempty------------t(1 row)SELECT ST_IsEmpty(ST_GeomFromText(’POLYGON EMPTY’));st_isempty------------t(1 row)SELECT ST_IsEmpty(ST_GeomFromText(’POLYGON((1 2, 3 4, 5 6, 1 2))’));st_isempty------------f(1 row)SELECT ST_IsEmpty(ST_GeomFromText(’POLYGON((1 2, 3 4, 5 6, 1 2))’)) = false;?column?----------t(1 row)SELECT ST_IsEmpty(ST_GeomFromText(’CIRCULARSTRING EMPTY’));st_isempty------------t(1 row)7.4.13 ST_IsRingST_IsRing — Returns TRUE if this LINESTRING is both closed and simple.Synopsisboolean ST_IsRing(geometry g);