La tua query deve essere prima dell'output:
Nota anche il typecast (integer) dell'id per proteggersi dalle iniezioni di sql.
Nota anche i problemi di sicurezza con $PHP_SELF http://php.about.com/od/learnphp/qt/_SERVER_PHP .htm
Ho cambiato il codice in $_SERVER['SCRIPT_NAME']
Nota anche di non utilizzare register_globals e disabilitalo nella configurazione se puoi (usa $_SERVER['SCRIPT_NAME'] instead of $SCRIPT_NAME`) :http://www.php.net/manual/ it/security.globals.php
Se impari php da un libro e questo è basato sul codice sorgente di questo libro, dovresti buttarlo via immediatamente.
<?php
//Database initialization
require_once("db_handler.php");
$conn = iniCon();
$db = selectDB($conn);
$query = "SELECT * FROM taxi_services ORDER BY SID";
$result2 = mysql_query($query, $conn);
if(isset($_POST["loadbtn"]))
{
$id = (integer) $_POST["codes"];
$query = "SELECT Name, Cost, Active FROM taxi_services WHERE SID = '$id' ";
$result = mysql_query($query, $conn);
$details = mysql_fetch_array($result);
$savedName = $details["Name"];
$savedCost = $details["Cost"];
$savedActive = $details["Active"];
}
?>
<html>
<head>
</head>
<body>
<div id="upserv">
<b id="caption2">Update location</b>
<br/><br/>
<form name="upServForm" action="<?php echo $_SERVER['SCRIPT_NAME']; ?>" method="post" >
<?php
$dropdown = "<select name='codes'>";
while($row = mysql_fetch_assoc($result2))
{
$dropdown .= "\r\n<option value='{$row['SID']}'>{$row['SID']}</option>";
}
$dropdown .= "\r\n</select>";
?>
Service ID <?php echo $dropdown; ?> <input type="submit" value="Load" name="loadbtn">
<table width="300" border="0">
<tr>
<td>Name</td>
<td><input type="text" name="upName" style="text-align:right" value="<? echo $savedName; ?>" /></td>
</tr>
<tr>
<td>Cost</td>
<td><input type="text" name="upCost" style="text-align:right" value="<? echo $savedCost; ?>" /></td>
</tr>
<tr>
<td>Active</td>
<td><input type="checkbox" name="upActive" value="<? echo $savedActive; ?>" /></td>
</tr>
</table>
</div>
<br/>
<div id="buttons">
<input type="reset" value="Clear" /> <input type="submit" value="Save" name="updatebtn" />
</div>
</form>
</body>
</html>
