反转 ST_Within 查询

Question

我正在使用 ST_Within，它工作正常，但我想选择不在凸包内的所有点，如何在 sql 中反转选择？

SELECT geom FROM pc_processing.pc_201406151141_top top

WHERE st_within(top.geom, (
SELECT st_convexhull(st_collect(geom)) as geom
FROM pc_processing.pc_201407060711_base))

Answer 1

ST_Within返回一个布尔值，所以你可以检查结果是false

SELECT geom FROM pc_processing.pc_201406151141_top top
WHERE st_within(top.geom, 
           (SELECT st_convexhull(st_collect(geom)) as geom
            FROM pc_processing.pc_201407060711_base
            )
      ) = false;