4. Write some code already

First we need a form to collect the zip code:

<p>Enter your 5 digit zip code:</p>
<form name="locate" method="POST"
    action="<?=$_SERVER['PHP_SELF']?>">
<input name="zip" maxlength="5" size="6" type="text" />
<input type="submit" value="Find" />
</form>

Below our form we create the code that connects to the database and finds the closest store. This example will show how to return only one store, but that can easily be changed. I’ll let the comments speak for themselves (remember to replace the items in double square brackets with your information):

<?php
// see if our zip code has been posted, and if it is a 5 digit #
if (isset($_POST['zip'])) {

  // remember to sanitize your inputs
  // this removes whitespace around the data and the next line makes sure its a 5 digit number
  $findzip = trim($_POST['zip']);
  if (preg_match("#^\d{5}$#",$findzip)) {

    // if we have the right kind of data, connect to the database
    $conn = mysql_connect('[[localhost]]','[[databse-user]]','[[database-password]]');

    // select the database with the tables we created in step 3
    mysql_select_db('[[database-name]]',$conn);

    // create a query that will select the zip code (if we can't find the user entered zip, we return an error)
    $query = "SELECT latitude,longitude,state,city FROM zip_codes WHERE zip=".$findzip." LIMIT 1";
    $result = mysql_query($query);
    if (mysql_num_rows($result) > 0) {

      // grab the latitude, longitude,state and city from our result
      list($flat,$flon,$fstate,$fcity) =  mysql_fetch_row($result);

      // now get all stores in the same state, or all stores if no states match
      // we want to reduce the amount of work the database has to do so we see if a state matches
      $query = "SELECT * FROM stores WHERE state='".$fstate."'";
      $result = mysql_query($query);
      if (mysql_num_rows($result) < 1) {
        $query = "SELECT * FROM stores";
        $result = mysql_query($query);
      }

      // now we process the stores to gather their data,
      //this result should not be empty, so I was lazy and didn't write an else case
      if (mysql_num_rows($result) > 0) {
        while($row = mysql_fetch_assoc($result)) {

          // first put all of the data for this store into an array, with the store id as the key
          $storeinfo[$row['id']] = $row;

          // get the store zip
          $dzip = $row['zip'];

          // query for the store's latitude and longitude
          $query = "SELECT latitude,longitude FROM zip_codes WHERE zip=".$dzip." LIMIT 1";
          $result2 = mysql_query($query);
          if (mysql_num_rows($result2) > 0) {
            list($dlat,$dlon) =  mysql_fetch_row($result2);

            // now get the distance from the user entered zip
            // this function can be found on the same site as the one where you downloaded the zip codes from
            $stores[$row['id']] = calcDist($flat,$flon,$dlat,$dlon);
          }
        }
      }

      // compare the distances (by sorting them least to greatest) to find the least
      asort($stores);

      // now we can display closest store
      // optionally you could loop over this to list multiple stores
      $store = $storeinfo[key($stores)];

      // here is the lazy way to print out the data - I leave the pretty printing up to you
      print_r($store);

      // we'll need this variable for the Yahoo Maps integration
      $maploc = $store['address1'] .", ".$store['city']." ".$store['state']." ".$store['zip'];
?>

// Paste Yahoo Maps API code from next section here.

<?php
    }
    //if can't find zip return error
    else {
      printError("The zip code you entered was not found in our database.  Please try another one.");
    }

  } else {
    printError("The zip code must be a 5 digit number. Please try again.");
  }
} else {
  //do nothing
}

// functions
function printError($e)
{
  echo "<p class='error'>$e";
}
function calcDist($lat_A, $long_A, $lat_B, $long_B)
{
  $distance = sin(deg2rad($lat_A))
                * sin(deg2rad($lat_B))
                + cos(deg2rad($lat_A))
                * cos(deg2rad($lat_B))
                * cos(deg2rad($long_A - $long_B));
  $distance = (rad2deg(acos($distance))) * 69.09;
  return $distance;
}
?>

Go to to step 5 »

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Category: Programming | 15,463 views | Posted: October 22nd 2007 07:00 am

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