PHP语法错误，请帮助

Question

解析错误：语法错误，意外';'在第11行，我试图找出我的错误，但没有成功。当我按照教程，代码是1/1视频，我不明白有什么问题。我在PHP初学者级别，所以任何人都可以帮助解决这个问题吗？

<?php
        if (isset($_POST['submit'])) {
    
    	include_once 'dbh.inc.php';
    
    	$first = mysql_real_escape_string($conn, $_POST['first']);
    	$mail = mysql_real_es1cape_string($conn, $_POST['mail']);
    	$pwd = mysql_real_escape_string($conn, $_POST['pwd']);
    
    	if (empty($first)||(empty($mail)||(empty($pwd)) {
    		header("Location: signup.php?signup=empty");
    		exit();
    	}
    	else 	{
    		if (!preg_match("/^[a-zA-Z]*$/", $first)){
    			header("Location: ../index.html?signup=invalid");
    			exit();
    		} else {
    			if (filter_var($mail, FILTER_VALIDATE_EMAIL)){
    				header("Location: ../index.html?signup=empty");
    				exit();
    			} else {
    				$sql = "SELECT * FROM users WHERE users_mail='$mail'";
    				$result = mysql_query($conn, $sql);
    				$resultCheck = mysql_num_rows($results);
    
    				if($resultCheck > 0) {
    					header("Location: ../index.html?signup=emailalredyinuse");
    					exit();
    				} else {
    					$hashedPWD = pasword_hash($pwd, PASWORD_DEFAULT);
    					$sql = "INSERT INTO users (user_first, user_mail, User_pwd) VALUES ('$first', '$mail', '$hashedPWD');";
    					$result = mysql_query($conn, $sql);
    					header("Location: ../index.html?signup=succsess");
    					exit();
    				}
    			}
    		}
    	}
    
    } else {
    	header("Location: ../index.html");
    	exit();
    }

Answer 1

if语句中有错误，这一行：

if (empty($first)||(empty($mail)||(empty($pwd)) {

应该是：

if (empty($first)||empty($mail)||empty($pwd)) {