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POhow to define a radial search area around a lat/lng position?
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  1. POhow to define a radial search area around a lat/lng position?
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    copied!<p>I am working on a project, where each user has its own coordinates lat / lng, extracted from google geocoder service...</p> <p>now I want to implement a search function -> you can enter the radius (km) and if someone is within the radius, the profile will pop up...</p> <p>it wasnt to difficult to get this to work, when the search area is actually a square, but how do I get this to work, with a circle as search area?</p> <p>here is the code, to build the "search" part of the mysql query:</p> <pre><code>// This is the location of the user who submitted the search function. mysql_select_db("$db_profile"); $sql = "SELECT location_lat, location_lng FROM location WHERE id = '$global_id'"; $sql = mysql_query($sql); $row = mysql_fetch_array($sql); // The coordinates of the user. $lat = $row['location_lat']; $lng = $row['location_lng']; // the entered radius in kilometers - here it is converted to degree (1° = 111km). $x_degree = $global_search_radius_value / 111; // define the search grid (it is a squere! but I want a circle!). $lat_neg = $lat - $x_degree; $lat_pos = $lat + $x_degree; $lng_neg = $lng - $x_degree; $lng_pos = $lng + $x_degree; // build the search part of the mysql query $heredoc_search_radius = &lt;&lt;&lt;EOD AND ($db_profile.location.location_lat &gt; '$lat_neg' AND $db_profile.location.location_lat &lt; '$lat_pos' AND $db_profile.location.location_lng &gt; '$lng_neg' AND $db_profile.location.location_lng &lt; '$lng_pos') EOD; </code></pre> <p>how can I use a circle instead of the squere!?</p>
 

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