สอบถามปัญหาเกียวกับ PHP+Javascript+MSSQL หน่อยครับ

<?php
function do_clash(){
$setting = $_POST['setting'];

if($setting == 0){
echo "display";
}else{

$sql1= "SELECT * FROM table1 WHERE ID = '".$_SESSION["username"]."'";
$sql_result1 = mssql_query($sql1);
$row1 = mssql_fetch_row($sql_result1);

if ($row1[0] == ""){
$sql = "INSERT INTO test (valus1,valus2,valus3) VALUES ('".$_SESSION["username"]."','0','0')";
mssql_query($sql);
}
mssql_query("UPDATE table2 SET valus2 = valus2+$setting WHERE ID = '".$_SESSION["username"]."'");
mssql_query("UPDATE table1 SET setting = 0 WHERE ID = '".$_SESSION["username"]."'");
echo "<script>navigate('index.php')</script>";
}

?>

                <? 	if (isset($_POST["clash"])){
			  do_clash();
			  } ?>

<? 
session_start(); 
$username = $_SESSION['username'];
if ($username == ''){
echo "<script>navigate('login.php')</script>"; 
exit();
} ?>