初始化几何类型的空列的合适值是多少

What is the suitable value to initialize an empty column of type geometry

我想为几何列设置一个默认值,表示它为空或 empty.for 例如,字符串最初初始化为空或“”以表示为 void/empty。几何的 null/empty 等价于什么。 几何列的值是多少表示它是空的。我尝试了 0"" 但不允许将它们插入到类型为 geometry

的列中

DEFAULT 添加到具有空几何的几何列,例如POINT:

CREATE TABLE t (
  id int,
  geom geometry(point,4326) NOT NULL DEFAULT 'POINT EMPTY'
);

它也适用于其他几何类型(以及它们的 ZM 扩展),例如:

SELECT 
  'POINT EMPTY'::geometry,
  'POLYGON EMPTY'::geometry,
  'LINESTRING EMPTY'::geometry,
  'MULTILINESTRING EMPTY'::geometry,
  'MULTIPOLYGON EMPTY'::geometry,
  'MULTIPOINT EMPTY'::geometry,
  'POLYHEDRALSURFACE EMPTY'::geometry,
  'TRIANGLE EMPTY'::geometry,
  'TIN EMPTY'::geometry,
  'GEOMETRYCOLLECTION EMPTY'::geometry;

-[ RECORD 1 ]----------------------------------------
geometry | 0101000000000000000000F87F000000000000F87F
geometry | 010300000000000000
geometry | 010200000000000000
geometry | 010500000000000000
geometry | 010600000000000000
geometry | 010400000000000000
geometry | 010F00000000000000
geometry | 011100000000000000
geometry | 011000000000000000
geometry | 010700000000000000

演示:db<>fiddle