为PostGIS编写原始SQL

我正在尝试使用PostGIS模板将一些数据输入到postgresql8.4数据库中。我不能 UPDATE

> 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

NULL 字段代替空间数据。我需要 更新 ,不是 INSERT