How to check if polygon in one table intersect with point and radius from second table?

Question

How can I check if polygon in one table intersect with point and radius from second table ?

• first table we have field (name: area) ,type geometry which contains polygon.
• second table we have 2 fields:
  • field (name: pt) ,type: geometry which contains point
  • field (name: radius) ,type: int

The geometry values in WKB format

I want to check if the polygon intersect with the circle (point + radius).

How can I do it ?

Answer 1

You can use the ST_Distance function to find the distance between the polygon and the point. If the distance between them is less than the radius, then the polygon would intersect with a circle around the point with that radius.

Example query:

SELECT *
FROM polygon_table, circle_table
WHERE ST_Distance(polygon_table.area, circle_table.pt) <= circle_table.radius;