检查数据库中是否已存在电子邮件

Question

I have a quiz form that is connected to my database, however I need to prevent duplicate email entries being inserted. I have tried the following:

//Check for duplicate email addresses
            function checkEmail($email){
                $sql = DB::select('email')->from('myquiz')->where('email','=','$email')->execute(); 

                $result = mysql_result(mysql_query($sql),0) ;

                if( $result > 0 ){
                die( "There is already a user with that email!" ) ;
                }//end if
            }

But I 'm still getting duplicate entries, here is all my code (may be I'm not running this in the correct place?)

 public function action_myquiz() {
    $this->template->styles['assets/css/myquiz.css'] = 'screen';
    $this->template->jscripts[] = 'assets/scripts/myquiz.js';
    $this->template->content = View::factory('quiz/myquiz');
        $this->template->content->thanks = false;
        if ($this->request->post('entry')) {
            $post = $this->request->post('entry');

            //Check for duplicate email addresses
            function checkEmail($email){
                $sql = DB::select('email')->from('myquiz')->where('email','=','$email')->execute(); 

                $result = mysql_result(mysql_query($sql),0) ;

                if( $result > 0 ){
                die( "There is already a user with that email!" ) ;
                }//end if
            }

            // save participant's info
            $stmt = DB::query(Database::INSERT, 'INSERT INTO `myquiz` (`first_name`, `last_name`, `email`, `confirm_email`)
                                                                        VALUES (:first_name, :last_name, :email, :confirm_email)');                                                     
            $stmt->param(':first_name', $post['first_name']);
            $stmt->param(':last_name', $post['last_name']);
            $stmt->param(':email', $post['email']);
            $stmt->param(':confirm_email', $post['confirm_email']);
            try {
                $stmt->execute();
            //  var_dump($post);
            } catch (Exception $e) {
                FB::error($e);
            }

            $this->template->content->thanks = true;
        }
    }

Answer 1

Two problems:

1. You're never calling your checkEmail() function so it's never running. You should either remove that code from the function or just call the function where it needs to run.
2. In that function you're checking that no email exists that literally equals "$email". PHP will only parse variables in double quotes - change that line to use where('email','=',"$email") instead.

Answer 2

将mysql_result更改为mysql_num_rows，如下面的第一个函数，然后尝试。

$result = mysql_num_rows(mysql_query($sql),0) ;

Answer 3

Your function is never executed. You will need to define the function outside the action_myquiz function and then call it. Also in the 'where' clause your not passing the email address in correctly and you can just use 'mysql_num_rows' to return the number of rows.

Try this:

//Check for duplicate email addresses
private function checkEmail($email) 
{
    $sql = DB::select('email')->from('myquiz')->where('email', '=', $email)->execute(); 

    $result = mysql_num_rows(mysql_query($sql),0) ;

   if( $result > 0 )
   {
       die( "There is already a user with that email!" ) ;
   }
}

public function action_myquiz() 
{
   $this->template->styles['assets/css/myquiz.css'] = 'screen';
   $this->template->jscripts[] = 'assets/scripts/myquiz.js';
   $this->template->content = View::factory('quiz/myquiz');
    $this->template->content->thanks = false;
    if ($this->request->post('entry')) {
        $post = $this->request->post('entry');

        // Check if email exists
        $this->checkEmail($_POST['email']);

        // save participant's info
        $stmt = DB::query(Database::INSERT, 'INSERT INTO `myquiz` (`first_name`, `last_name`, `email`, `confirm_email`)
                                                                    VALUES (:first_name, :last_name, :email, :confirm_email)');                                                     
        $stmt->param(':first_name', $post['first_name']);
        $stmt->param(':last_name', $post['last_name']);
        $stmt->param(':email', $post['email']);
        $stmt->param(':confirm_email', $post['confirm_email']);
        try {
            $stmt->execute();
        //  var_dump($post);
        } catch (Exception $e) {
            FB::error($e);
        }

        $this->template->content->thanks = true;
    }
}

A couple of additional points:

• Raj is correct that a Try/Catch block might be better
• Ensure your data is escaped before passing into SQL queries, your framework might be doing this for you.

Answer 4

In PHP you can't place a function inside another function. So you need to place it outside your action_myquiz function. You'll also want to change mysql_result to mysql_num_rows . Something like this

//Check for duplicate email addresses
function checkEmail($email){
    $sql = DB::select('email')->from('myquiz')->where('email','=',"$email")->execute(); 
    $result = mysql_num_rows(mysql_query($sql),0) ;

    if( $result > 0 ){
        return true;
    }

    return false;
}

//Now start your other function
function checkEmail($email){

Then inside your action_myquiz function you need to call your checkEmail function. Like

if(checkEmail($email) === false) {
    //Proceed with insert
} else {
    //Don't do insert
}