Query locations in a circle of $max_distance around $input_latitude, $input_longitude

locationquery.sql

SELECT 
    l.*, 
    ( 
        6371
        * acos( 
            cos( 
                radians( $input_latitude ) 
            ) 
            * cos( 
                radians( l.latitude ) 
            ) 
            * cos( 
                radians( l.longitude ) - radians( $input_longitude ) 
            ) 
            + sin( 
                radians( $input_latitude ) 
            ) 
            * sin( 
                radians( l.latitude )
            ) 
        ) 
    ) AS distance
FROM locations l
WHERE 
    l.id != 0  -- or some other conditions thate make more sense
HAVING distance < $max_distance
ORDER BY distance
LIMIT 0, 10;