First array element getting overwritten by the second when getting data from db using PHP

I have a few lines of code that start something like this:

$trailheads = array();
// Then a db call with a query.  Then loop through the results.

// This gives a diff value every time, so here we are still ok
$trailhead->trailhead_name = $row['trailhead_name']; 

// Before the look iteration ends, I do something like this:
arra开发者_JS百科y_push ( $trailheads , $trailhead );
// But I could have done this with the same result:
$trailheads[] = $trailhead; 

And once I exit the loop, I do print_r and it shows that the second of the two rows returned by the query over-wrote the first.

Here is the full version of the loop:

    while($row = mysql_fetch_assoc($trailhead_result))
    {
        $trailhead->trailhead_name = $row['trailhead_name'];


        $trailhead->park_id = $row['park_id'];
        $trailhead->trailhead_id = $row['trailhead_id'];
        $trailhead->trailhead_description = $row['trailhead_description'];
        $trailhead->parking = $row['parking'];
        $trailhead->lat = $row['lat'];
        $trailhead->lng = $row['lng'];
        $trailhead->is_free = $row['is_free'];
        $trailhead->parking_spots = $row['parking_spots'];
        $trailhead->cost_details = $row['cost_details'];

        $trailheads[] = $trailhead;
    }

If that's your full loop, then one problem is that you're not initializing $trailhead inside the loop. Do this:

while($row = mysql_fetch_assoc($trailhead_result))
{
    $trailhead = new trailhead();
    $trailhead->trailhead_name = $row['trailhead_name'];
    $trailhead->park_id = $row['park_id'];
    $trailhead->trailhead_id = $row['trailhead_id'];
    $trailhead->trailhead_description = $row['trailhead_description'];
    $trailhead->parking = $row['parking'];
    $trailhead->lat = $row['lat'];
    $trailhead->lng = $row['lng'];
    $trailhead->is_free = $row['is_free'];
    $trailhead->parking_spots = $row['parking_spots'];
    $trailhead->cost_details = $row['cost_details'];

    $trailheads[] = $trailhead;
}

I have to assume that the object $trailhead is a class called trailhead. If it's not, use whatever class is correct in place of new trailhead().