为PostGIS编写原始SQL

Question

我正在尝试使用PostGIS模板将一些数据输入到PostgreSQL 8.4数据库中。我无法UPDATE多边形：

> UPDATE my_table SET coords = POINT(1, 1)
UPDATE 0 1

> UPDATE my_table SET box = POLYGON(((1, 1), (2, 3), (3, 3), (1, 1)))
ERROR:  function polygon(record) does not exist

> UPDATE my_table SET box = POLYGON((1, 1), (2, 3), (3, 3), (1, 1))
ERROR:  function polygon(record, record, record, record) does not exist

> UPDATE my_table SET box = POLYGON(1, 1, 2, 3, 3, 3, 1, 1)
ERROR:  function polygon(numeric, numeric, numeric, numeric, numeric, numeric, numeric, numeric) does not exist

> UPDATE my_table SET box = ((1, 1), (2, 3), (3, 3), (1, 1))
ERROR:  column "box" is of type polygon but expression is of type record

如何插入多边形？请注意，表中已存在数据，NULL个字段代替空间数据。我需要UPDATE，而不是INSERT，但这不应该有所作为。

Answer 1

您应该使用Geometry constructors在表格中加载新的几何图形，特别是St_GeomFromText函数：

UPDATE my_table SET box = ST_GeomFromText('POLYGON ((1 1), (2 3), (3 3), (1 1))');

几何体以WKT（Well-Known Text）格式定义。

Answer 2

尝试：

UPDATE my_table SET box = '((1, 1), (2, 3), (3, 3), (1, 1))'::polygon;

据我所知，大多数几何类型一般都需要引号。