updating a database using UPDATE

[wxdqz]

Im trying to update a database but it isnt working.

can anyone offer any suggestions why it doesnt?

any help is very much appreciated as its beginning to do my head in!! :S

TIA Rob

$array ["custid"]= trim ($array["custid"]);
$array ["nextinv"]= trim ($array["nextinv"]);
$array ["paygot"]= trim ($array["paygot"]);
$array ["overdueby"] = trim ($array["overdueby"]);



$Host = "localhost";
$User = "robert";
$Password = "robert";
$DBName = "customer_records";


$Link = mysql_connect ($Host, $User, $Password);

$Query = "UPDATE payment_details
set paygot = '$array[paygot]' WHERE payment_details.custid = '$array[custid]'
AND set nextinv ='$array[nextinv]' WHERE payment_details.custid = '$array[custid]'";
$Result = mysql_db_query ($DBName, $Query, $Link);

print ("$Query\n");

if (mysql_db_query ($DBName, $Query, $Link )){
print ("it worked\n");
}else {
print ("oh dear\n");
}

mysql_close ($Link);

?>