รบกวนพี่ๆๆครับ ช่วยดูโค้ด เปลี่ยนรหัสผ่านให้ผมหน่อยครับ Error ครับ แก้ไม่ได้สักที

$sql = "select Username from member where Username ='$Username' and Password  ='$Oldpassword'";
$result = mysql_query($sql) or die (mysql_error());

$sql = "select Username from member where Username ='$Username' Password and ='$Oldpassword'";
$result = mysql_query($sql);

$sql = "SELECT Username FROM member  WHERE Username ='$Username' AND Password = '$Oldpassword' LIMIT 1";

<?
$host="localhost";
$username="root";
$password="1234";
$db="TBmember";
$con=mysql_connect( $host,$username,$password); 

$Oldpassword = trim($_POST["Oldpassword"]);
$Password = trim($_POST["Password"]);
$Re_password = trim($_POST["Re_password"]);

$sql = "SELECT Username FROM member  WHERE Username ='$Username' AND Password = '$Oldpassword' LIMIT 1";
$result = mysql_query($sql) or die(mysql_error());
$num = mysql_num_rows($result);
if ($num==0){
	echo"<script>alert('รหัสผ่านเก่าไม่ถูกต้องครับ')</script>";
        echo"<meta http-equiv='refresh' content='0;url=chang_pwd.php'>";  

} else if ($Password != $Re_password) {
	echo"<script>alert('รหัสผ่านไม่เหมือนกันครับ')</script>";
	echo"<meta http-equiv='refresh' content='0;url=chang_pwd.php'>";
} else {
$sql1 = "UPDATE member SET Password = '$Password' WHERE Username='$Username' ";
mysql_query("SET NAMES utf8");
$result=mysql_query($sql1);
   if($result){
	echo "<script>alert('คุณได้เปลี่ยนรหัสผ่านใหม่เรียบร้อยแล้วครับ')</script>";  
	echo "<meta http-equiv='refresh' content='0;url=Index.php'>";  
   }
}
	
?>