检查后插入记录

Question

我有PHP代码，可以检查电子邮件是否已经存在。问题是即使它不存在，它也将始终打印“电子邮件已存在”。该数据库运行良好。

 $b = mysqli_query($con ,"insert into form2 (Email, Password) values ('$email', '$pass')");
 $sql = "SELECT `Email`FROM `form2` WHERE `Email`='".$email."'";
 $res=mysqli_query($con,$sql);
  if (mysqli_num_rows($res) > 0)
   {
        die("Email already exists");
     }

   else
   {
  if($resultSet){
     $resultSet = mysqli_query($con,$b);
        echo"Added successfully";}

     else
         die("Not added");
}