How Can We Identify Overlapping Marker Radiuses Using SQL?

Determining Overlapping Markers within Radius

To identify people who fall within overlapping marker radiuses, we utilize geometric principles and convert distances to kilometers for consistency.

The equation for a point (x, y) within a circle with center (x1, y1) and radius r is:

(x - x1)^2 + (y - y1)^2 <= r^2

Since degrees are converted to kilometers using the formula 1 degree = 111.12 km, the equation becomes:

((x - x1) * 111.12)^2 + ((y - y1) * 111.12)^2 = 4 (for radius = 2km)

With this equation, the SQL statement to retrieve results that overlap any marker radii can be formulated as follows:

<code class="sql">SELECT A.user_id, A.radius_id, A.latitude, A.logitude
FROM UserA AS A, 
(SELECT user_id, latitude, longitude 
FROM UserB 
WHERE user_id = 8) AS B
WHERE (POW((A.latitude - B.latitude) * 111.12, 2) + POW((A.longitude - B.longitude) * 111.12, 2)) <= 4</code>

In this query, UserA's records are represented by table A, and UserB's records with ID 8 are represented by table B. The POW() function raises a number to a power, and it is used here to square the difference between coordinates.

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