ST_IsEmpty
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## Name

ST_IsEmpty — Tests if a geometry is empty.

## Synopsis

`boolean ST_IsEmpty(`geometry geomA`)`;

## Description

Returns true if this Geometry is an empty geometry. If true, then this Geometry represents an empty geometry collection, polygon, point etc.

SQL-MM defines the result of ST_IsEmpty(NULL) to be 0, while PostGIS returns NULL.

This method implements the OGC Simple Features Implementation Specification for SQL 1.1. s2.1.1.1

This method implements the SQL/MM specification. SQL-MM 3: 5.1.7

This method supports Circular Strings and Curves

Changed: 2.0.0 In prior versions of PostGIS ST_GeomFromText('GEOMETRYCOLLECTION(EMPTY)') was allowed. This is now illegal in PostGIS 2.0.0 to better conform with SQL/MM standards

## Examples

    SELECT ST_IsEmpty(ST_GeomFromText('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)

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