Assess Whether a Point Lies Within a Defined Area

Check if a Point is Within a Polygon

Write a MySQL query to verify if a given point lies inside a specified polygon using ST_Within.

Solution:

-- Check if a specific point is located within a defined polygon.
SELECT 

    -- Use the ST_Within function to determine whether the given POINT geometry 
    -- is contained within the specified POLYGON geometry. The result is returned as 'isWithin'.
    ST_Within(
        ST_GeomFromText('POINT(-73.97 40.78)'),  -- Define the POINT geometry to check.
        ST_GeomFromText('POLYGON((-73.99 40.77, -73.95 40.77, -73.95 40.79, -73.99 40.79, -73.99 40.77))')  -- Define the POLYGON geometry.
    ) AS isWithin;

Explanation:

• Purpose of the Query:
• The goal is to determine whether a point is located within a polygon.
• This demonstrates the ST_Within function for spatial containment tests.
• Key Components:
• ST_Within(point, polygon) : Returns 1 (true) if the point is inside the polygon.
• Well-Known Text (WKT) format is used to define the point and polygon.
• Real-World Application:
• Useful for geofencing applications and spatial queries based on regions.

Notes:

• Ensure both geometries share the same spatial reference system.

For more Practice: Solve these Related Problems:

• Write a MySQL query to check if a given point is inside a polygon stored in the "Regions" table using ST_Within.
• Write a MySQL query to determine if a point generated by ST_GeomFromText falls within a dynamically defined polygon and return a boolean result.
• Write a MySQL query to verify containment of a point in the "Boundaries" table using ST_Within, aliasing the result as "inside".
• Write a MySQL query to filter records from "Zones" where a provided point lies within the polygon area stored in a spatial column.

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• Hands-on MySQL Spatial Data Exercises Home. ↩
• MySQL Exercises Home ↩

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