其他部分不起作用，而条件在PHP中为假

Question

why the else part is not working? whereas condition is false. here is the code. please suggest:

function SignUp() { 
    if(isset($_POST['email'])){
    $query = mysql_query("SELECT * FROM register WHERE email = '$_POST[email]' AND password = '$_POST[password]'") or die(mysql_error()); 
    if(!$row = mysql_fetch_array($query) or die(mysql_error())) { 
        NewUser();} 
    else{ 
        echo "SORRY...YOU ARE ALREADY REGISTERED USER...";} 
    } 
  } 

Answer 1

I think you have wrote some wrong syntax. Please replace code with below code.

function SignUp() { 
    if(isset($_POST['email'])){
    $query = mysql_query("SELECT * FROM register WHERE email = '".$_POST['email']."' AND password = '".$_POST['password']."'") or die(mysql_error()); 
    if(!$row = mysql_fetch_array($query) or die(mysql_error())) { 
        NewUser();
    } 
    else{ 
        echo "SORRY...YOU ARE ALREADY REGISTERED USER...";

    } 
    } 
  }

Answer 2

Note :- In developement mode, You should ON your error reporting .

Also mysql_* functions are deprecated in newer versions of PHP. So use mysqli or PDO .

Write below lines in top of your php file to see all errors, warnings and notices.

error_reporting(E_ALL);
ini_set("display_errors", 1);

Rewrite your function as below:-

function SignUp() { 
    if(isset($_POST['email'])){
    $query = mysql_query("SELECT * FROM register WHERE email = '$_POST[email]' AND password = '$_POST[password]'") or die(mysql_error());
        // $query returns true or false
        if($query) { 
            NewUser();
        } 
        else{ 
            echo "SORRY...YOU ARE ALREADY REGISTERED USER...";
        } 
    } 
} 

Hope it will help you :)

Answer 3

Change your condition and use mysql_num_rows() as:

function SignUp() { 

    if(isset($_POST['email']))
    {
        $query = mysql_query("
            SELECT * FROM register WHERE 
            email = '$_POST[email]' 
            AND password = '$_POST[password]'
            ") or die(mysql_error()); 

        // if record exist
        if(mysql_num_rows($query) > 0){
            echo "SORRY...YOU ARE ALREADY REGISTERED USER...";
        }
        else{
            NewUser(); // register new user
        } 
    } 
} 

---

From your comments:

> use of mysql_num_rows() display blank screen. – Anks

Add error_reporting() at top in your file and check what errors are you getting.

ini_set("display_errors", 1);
error_reporting(E_ALL);    

Side Note:

Please use mysqli_ * or PDO extension because mysql_* is deprecated and closed in PHP 7.

Mysqli Query PHP Manual