เกี่ยวกับการบันทึกข้อมูลลง ฐานข้อมูล ช่วยชี้แนะทีครับ

<?
if($username == "" and $password == "" and $confirm == "" and $name == "" and $lastname == "")
{
echo "<script>alert(' data error ');history.back();</script>";
exit();
}else{

$sql = "insert into member values('','$username','$password','$name','$lastname','$gender','$birthday','$address','$email')";
mysql_query($sql) or die("error=$sql");
echo "<script>alert(' Register Success ');
window.location='login.php';</script>";
}
?>

function validation(){
if(document.getElementById('name').value == ""){
alert("กรุณาระบุชื่อ");
document.getElementById('name').focus();
return false;
}else{
document.form2.submit();
return true;
}
}

<?php if(empty($_POST)) {?>

<form id="form1" name="form1" method="post" action="">
  <label>
  <input type="text" name="username" id="username" />
  </label>
  <p>
    <label>
    <input type="text" name="password" id="password" />
    </label>
  </p>
  <p>
    <label>
    <input type="submit" name="button" id="button" value="Submit" />
    </label>
  </p>
</form>

<?php } else { ?>

<?
$username = $_POST['username'];
$password = $_POST['password'];

if($username == "" or $password == "")
{
echo "<script>alert(' data error ');history.back();</script>";
exit();
}else{

echo "ข้อมูลไม่ได้ว่างเลย";

/*$sql = "insert into member values('','$username','$password','$name','$lastname','$gender','$birthday','$address','$email')";
mysql_query($sql) or die("error=$sql");
echo "<script>alert(' Register Success ');
window.location='login.php';</script>";*/
}
?>

<?Php } ?>