newsletter question

[Janjan]

Hi guys,

I'm working on my first newsletter script, until now it works.
But I also would like to make a warning in my PHP script that tells the user that he had already entered his email adres.
And I also would like to make the emailadres case sensitive.
How can I do this?

news.php:

<?php

if (isset($POST['action'])) {
$email = $POST['e'];

$email = strip_tags($email);
$email = trim($email);

if (strlen($email) > 255) {
    $msg  = "Your email<strong>$email</strong> is to long. ";
    $msg .= "make it less than 255 chars. ";
} else {
    require_once('is_email.inc.php');      
    if (is_email($email)) {           
        $action = $_POST['action'];          
        if ($action === "submit" or $action === "erase") {


 if ($action == "submit") {
     $sql         = "INSERT INTO newsletter (email) VALUES ('$email');";
     $msg     = "Your <strong>$email</strong> is added. ";
     $msg    .= "You can remove your email by clicking on the erase-button. ";
     $email  = "";
 }
 if ($action == "erase") {
     $sql         = "DELETE FROM newsletter WHERE email = '$email';";
     $msg    = "Your emailadres <strong>$email</strong> has been removed. ";
     $msg   .= "Subscribe yourself by entering your mail in the input-field. ";
 }

require_once('connect.php');

    $connection = mysql_connect(MYSQL_SERVER, MYSQL_USER, MYSQL_PW) or die("Unable to connect: " . mysql_error());
      mysql_select_db("test") or die("Failed to open database: " . mysql_error());

      mysql_query($sql) or die("Query failed: " . mysql_error());

      mysql_close($connection);

} else {

     $email  = htmlentities($email, ENT_QUOTES);
     $msg     = 'Unknown error. ';
     $msg    .= 'Check your entered email. ';

}
} else {
$email = htmlentities($email, ENT_QUOTES);

      if (strlen($email) < 1) {
      $msg = "U must enter a <strong>e-mailadres</strong>. ";

} else {
$msg = "<strong>$email</strong> is not a valid mailadres. ";
$msg .= "Check your mail. ";
}
}
}
} else {
$email = "";

$msg  = "";
}

?>

Thank you for your help!

[bradgrafelman]

When posting PHP code, please use the board's [noparse]

..

[/noparse] bbcode tags as they make your code easier to read and analyze. You should go back and edit your post to include the tags.

As for your question, the best way to prevent duplicate email addresses would be to add a UNIQUE (or PRIMARY) index on the email column in the database. Then, when you do your INSERT query, check if it fails with an error number of 1062 - 'duplicate data for key' (or something like that). That error code means that the email address entered was found in one of the existing rows.

As for the case sensitive part... why would you want the email address to be case sensitive? [e-mail] is the same e-mail address as [e-mail]... why would you want to consider them two different addresses?