## How to Improve the Accuracy of Radius-Based Location Searches in MySQL?

Improving Accuracy in MySQL Longitude and Latitude Query for Radius-Based Search

When performing radius-based location searches in mySQL, a common issue is obtaining results that deviate significantly from the specified radius. This discrepancy often arises from errors in the distance calculation formula, leading to inaccurate distance measurements.

To remedy this problem, consider a refined query that utilizes a slightly different distance calculation method:

SELECT
    `id`,
    (
        6371 *
        acos(
            cos( radians( :lat ) ) *
            cos( radians( `lat` ) ) *
            cos(
                radians( `long` ) - radians( :long )
            ) +
            sin(radians(:lat)) *
            sin(radians(`lat`))
        )
    ) `distance`
FROM
    `location`
HAVING
    `distance` < :distance
ORDER BY
    `distance`
LIMIT
    25

In this query:

• :lat and :long represent the user-defined coordinates.
• lat and long denote the coordinates stored in the database.
• :distance corresponds to the specified radius, measured in miles (or kilometers if 3959 is replaced with 6371).

This formula calculates the distance based on the Haversine formula, which provides more accurate results than the formula used in your original query. By incorporating this revised formula, you can refine your radius search functionality, ensuring that the returned results adhere to the specified radius range.

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