Updating 2 rows together in mysql using PHP

[idnoble]

Hello,
I've created a script to help update my database, but it seems I have an error in the mysql syntax as I kept getting this error message each time i run the script in my browser

Error: You have an error in your SQL syntax near 'set Last_name = '' where Last_name = 'Pioneer'' at line 4

I am trying to update 2 fields from 2 different rows together, can someone please help me with this. My script is below.

 <?php
//create short variable names
$OldFirstname = $HTTP_POST_VARS['OldFirstname'];
$OldLastname = $HTTP_POST_VARS['OldLastname'];
$NewFirstname = $HTTP_POST_VARS['NewFirstname'];
$NewLastname = $HTTP_POST_VARS['NewLastname'];

//check all fields has been completed
if (!$OldFirstname || !$OldLastname || !$NewFirstname || !$NewLastname)
{
echo '<p><strong>You have not completed all required fields. Go back and try again.</strong></p>';
exit;
}

//connect to the database
$session = mysql_connect("localhost", "root", "platinum")or die(mysql_error());
if(!$session)
{
echo 'Error: Could not to the database please try again later.';
exit;
}

//select database
mysql_select_db('xplosive')or die(mysql_error());

//query the database
$query = "Update customer_account
          set First_name = '$NewFirstname'  

		  where First_name = '$OldFirstname' and
		  set Last_name = '$NewLastName'
		  where Last_name = '$OldLastname'";

$result = mysql_query($query);
if(!$result)
  echo ("<p>Error: ". mysql_error() ."</p>");

else
  echo '<p style "font-style: 14pt; color:#CC9900"><strong>Your name has been changed.</strong></p>';

?>

[LordShryku]

Updates should be comma delimeted after the set operator. If this is the same record, then use the query below. Otherwise, you'll need to do them seperately.

$query = "UPDATE customer_account
             SET First_name = '$NewFirstname',
                 Last_name = '$NewLastName'
           WHERE First_name = '$OldFirstname'
             AND Last_name = '$OldLastname'";

[nbennett]

so in order to do a multiple row update, you need to do multiple SET functions? does the VALUES (x,y) syntax not work (ala the INSERT syntax)?

ie, you have to do:

UPDATE item
SET variable1 = $myVar WHERE item_id =

$item_id
AND
SET variable2 = $myVar2 WHERE item_id =

$item_id2

rather than:

UPDATE item SET variable1, variable2 VALUES ($myVar1),($myVar2) WHERE item_id = ($item_id),($item_id2)

? or is this something that REPLACE does?

thanks