two query updates doesn't work - php

Question

hi guys I got a little problem while I am was trying to updates my table.
I just explain you my situation:
index.php
<?php
$query = mysql_query("SELECT * FROM `references` ORDER BY `ID` ASC") or die(mysql_error());
while($referenc = mysql_fetch_assoc($query)){
echo '
<tr>
<td>'.$referenc['name'].'</td>
<td>'.$referenc['url'].'</td>
<td>'.$referenc['date'].'</td>
<td>up</td>
<td>down</td>
<td>edit</td>
</tr>
';
}
?>
how you can see I have there two links for up and down.
after click on one of that link I am going on updatetest.php
updaterest.php
f.e
move = up
position = 2;
id = 2;
<?php
$move = $_GET['move'];
if($move == "up"){
$getcurrentid = $_GET['id'];
$moveup = $_GET['position']-1;
$getprevposition = $_GET['position']-1;
$position = $_GET['position'];
$query = mysql_query("UPDATE `references` SET `position` = '$moveup' WHERE `references`.`ID`='$getcurrentid'") or die(mysql_error());
$query2 = mysql_query("UPDATE `references` SET `position` = '$position' WHERE `references`.`position`='$getprevposition'") or die(mysql_error());
}
else{echo'down';}
?>
Now it doing always just one update if I comment first update second one is working fine if I comment second update first one is working fine but if I uncomment it and wanna do it together its always doing just one update. I looking for some way how to do 2 updates in same time
any ideas ?

Answer 1

You need to do the queries in another order. $moveup and $getprevposition have the same value, so you are currently doing something like this
change position to new where id = x
change position to old where position = new
Since you just changed position to new, the second WHERE will catch the item you already edited (and undo your edit). Instead, you should do it like this
change position to old where position = new
change position to new where id = x
Now you don't have a conflict, as the row you really want to change doesn't yet have position = new.