我的 php 没有将值输入到 sql 数据库中，我的代码有什么问题？

Question

I'm having this problem where I have a registration form and I am using PHP and MySQL. The problem is that even when all the data is valid it wont enter the information into the database. I know the database is connected because I can use it with the login part of my website. I think it is the problem with the email and username cross check against the database but I am not sure. Is the positioning of the curly braces or alot more complex?

<?php
  include_once('db.php');

  $name = mysql_real_escape_string( $_POST["name"] );
  $username = mysql_real_escape_string( ($_POST["username"]) );
  $password = mysql_real_escape_string( md5 ($_POST["password"]) );
  $repeatpassword = mysql_real_escape_string( $_POST['repeatpassword'] );
  $email = mysql_real_escape_string( $_POST["email"] );
  $confirmemail = mysql_real_escape_string( $_POST['confirmemail'] );

  // the below if statement is for when the user does NOT have JS enabled in            their browser
  if(empty($name) || empty($username) || empty($password) || empty($email)){
    echo "(*) indicate that the fields are mandatory.";
    exit();
  }

  if($email == $confirmemail){
    exit();
  }else{
    echo "Your Email address does not match.";
  }

  if($email == $repeatpassword){
    exit();
  }else{
    echo "Your Passwords do not match.";
    exit();
}

  $res = mysql_query("SELECT username FROM users WHERE username='$username'");
  $row = mysql_fetch_row($res);
  $res1 = mysql_query("SELECT email FROM users WHERE email='$email'");
  $row1 = mysql_fetch_row($res1);

  if( $row > 0 ){
    echo nl2br("The username $username is already in use");
  }else{

        if( $row1 > 0 ){
            echo nl2br("the email address $email is already in use");
        }else{

        $sql = "INSERT INTO users VALUES('','$name',  '$username', '$password', '$email')";

        if( mysql_query($sql) ){
            echo "Inserted Successfully";
        }else{
        echo "Insertion Failed";
        }
    }  
}

?>

Answer 1

if($email == $confirmemail) {
    exit();
}
else {
    echo "Your Email address does not match.";
}

So what you're doing in the above code is "if email and confirmation email are the same, stop the script execution else print out 'Your Email address does not match.' and continue execution".

if  ($email == $repeatpassword) {
  exit();
}
else {
  echo "Your Passwords do not match.";
  exit();
}

And here you are saying if "email and repeatpassword are the same (???), stop script execution else print out 'Your Passwords do not match.' and also stop script execution".

So because of this logic obviously you never reach the code to insert data to database.