How to prevent repeat sign ups from being put into db?

[BrentonHale]

Hi, I was needing some help with preventing repeat sign ups.  I need a query to check the submitted email address ($e) is currently in the database by attempting to select that record.  If it's not in the database, then it's safe to register.

 

Here is the existing code (with/out) the prevention of repeated sign ups.  Please tell me on which lines (where to add) the code you provide in your replies.

 

<?php # Script 7.3 - register.php

$page_title = 'Register';
include ('./header.html');

// Check if the form has been submitted.
if (isset($_POST['submitted'])) {

$errors = array(); // Initialize error array.

// Check for a first name.
if (empty($_POST['first_name'])) {
$errors[] = 'You forgot to enter your first name.';
} else {
$fn = trim($_POST['first_name']);
}

// Check for a last name.
if (empty($_POST['last_name'])) {
$errors[] = 'You forgot to enter your last name.';
} else {
$ln = trim($_POST['last_name']);
}

// Check for an email address.
if (empty($_POST['email'])) {
$errors[] = 'You forgot to enter your email address.';
} else {
$e = trim($_POST['email']);
}

// Check for a password and match against the confirm password.
if (!empty($_POST['password1'])) {
if ($_POST['password1'] != $_POST['password2']) {
$errors[] = 'Your password did not match the confirmed password.';
} else {
$p = trim($_POST['password1']);
}
} else {
$errors[] = 'You forgot to enter your password.';
}

if (empty($errors)) { // If everythings okay.

// Register the user in the database.
require_once ('mysql_connect.php'); // Connect to the db.



$link = mysql_connect('localhost', 'username', 'password');
if (!$link) {
    die('Could not connect: ' . mysql_error());
}
echo 'Connected successfully';
mysql_close($link);



$link = mysql_connect('localhost', 'username', 'password');
if (!$link) {
    die('Not connected : ' . mysql_error());
}

// make sitename the current db
$db_selected = mysql_select_db('sitename', $link);
if (!$db_selected) {
    die ('Can\'t use sitename : ' . mysql_error());
}

// make sitename the current db
$db_selected = mysql_select_db('sitename', $link);
if (!$db_selected) {
    die ('Can\'t use sitename : ' . mysql_error());
}




// Make the query.
$query = "INSERT INTO users (first_name, last_name, email, password, registration_date) VALUES ('$fn', '$ln', '$e', SHA

('$p'), NOW() )";
$result = @mysql_query ($query); // Run the query.
if ($result) { // If it ran OK.

// Send an email, if desired.

// Print a message.
echo '<h1 id="mainhead">Thank you!</h1>
<p>You are now registered.  In Chapter 9 you will actually be able to log in!</p><p><br/></p>';

// Include the footer and quit the script (to not show the form).
include ('./footer.html');
exit();

} else { // If it did not run OK.
echo '<h1 id="mainhead">System Error</h1>
<p class="error">You could not be registered due to a system error.  We apologize for any inconvenience.</p>'; // Public message.
echo '<p>' . mysql_error() . '<br/><br/>Query: ' . $query . '</p>'; // Debugging message.
include ('./footer.html');
exit();
}

mysql_close(); // Close the database connection.

} else { // Report errors.

echo '<h1 id="mainhead">Error!</h1>
<p class="error">The following error(s) occurred:<br/>';
foreach ($errors as $msg) { // Print each error.
echo " - $msg<br/>\n";
}
echo '</p><p>Please try again</p><p><br/></p>';

} // End of if (empty($errors)) IF.

} // End of the main Submit conditional.
?>
<h2>Register</h2>
<form action="register.php" method="post">
<p>First Name: <input type="text" name="first_name" size="15" maxlength="15" value="<?php if (isset($_POST

['first_name'])) echo $_POST['first_name']; ?>" /></p>
<p>Last Name: <input type="text" name="last_name" size="15" maxlength="30" value="<?php if (isset($_POST['last_name'])) 

echo $_POST['last_name']; ?>" /></p>
<p>Email Address: <input type="text" name="email" size="20" maxlength="40" value"<?php if (isset($_POST['email'])) echo 

$_POST['email']; ?>" /></p>
<p>Password: <input type="password" name="password1" size="10" maxlength="20" /></p>
<p>Confirm Password: <input type="password" name="password2" size="10" maxlength="20" /></p>
<p><input type="submit" name="submit" value="Register" /></p>
<input type="hidden" name="submitted" value="TRUE" />
</form>
<?php
include ('./footer.html');
?>

 

I tried using this code, but the script stopped running.

$query = "SELECT user_id FROM users WHERE email='$e'";$result =  mysql_query($query);if (mysql_num_rows($result) == 0) {

and I tried this code as well:

 

} else {echo '<h1="mainhead">Error!</h1><p class="error">This email address has already been registered.</p>;}

 

[btherl]

Did you try using both of those pieces of code together? 

 

Also can I suggest using indentation like this:

 

if (foo) {
    something;
    if (bar) {
        somethingelse;
    } else {
        anotherthing;
    }
}

 

That makes it much easier to understand how the program works.  It will help you find bugs faster, and also help us to understand your code so we can answer your question

 

The basic rule is that whenever you start an "if" or "while" or "foreach" or anything which has a "{" following it, then you should start indenting.  When you reach the "}" at the end, then you go back to the previous indentation level.

[BrentonHale]

Yes, I used both together.  Still not working.  I have indented where I seen a "  {  " .  I hope this helps everyone out and makes it easier/faster to see what's wrong with the code.  I'm inserting the updated code.

 

<?php # Script 7.3 - register.php

$page_title = 'Register';
include ('./header.html');

// Check if the form has been submitted.
if (isset($_POST['submitted'])) {

    $errors = array(); // Initialize error array.

// Check for a first name.
if (empty($_POST['first_name'])) {
    $errors[] = 'You forgot to enter your first name.';
        } else {
        $fn = trim($_POST['first_name']);
        }

// Check for a last name.
if (empty($_POST['last_name'])) {
    $errors[] = 'You forgot to enter your last name.';
    } else {
    $ln = trim($_POST['last_name']);
    }

// Check for an email address.
if (empty($_POST['email'])) {
    $errors[] = 'You forgot to enter your email address.';
    } else {
    $e = trim($_POST['email']);
    }

// Check for a password and match against the confirm password.
if (!empty($_POST['password1'])) {
    if ($_POST['password1'] != $_POST['password2']) {
        $errors[] = 'Your password did not match the confirmed password.';
        } else {
            $p = trim($_POST['password1']);
            }
    } else {
        $errors[] = 'You forgot to enter your password.';
        }

if (empty($errors)) { // If everythings okay.

// Register the user in the database.
require_once ('mysql_connect.php'); // Connect to the db.

$link = mysql_connect('localhost', 'username', 'password');
if (!$link) {
    die('Could not connect: ' . mysql_error());
}
echo 'Connected successfully';
mysql_close($link);

$link = mysql_connect('localhost', 'username', 'password');
if (!$link) {
    die('Not connected : ' . mysql_error());
}

// Check for previous registration.

$query = "SELECT user_id FROM users WHERE email='$e'";
$result =  mysql_query($query);
if (mysql_num_rows($result) == 0) {

    } else { 

echo // Already registered.

'<h1 id="mainhead">Error!</h1>
<p class="error">This email address has already been registered.</p>;
}

// make sitename the current db
$db_selected = mysql_select_db('sitename', $link);
if (!$db_selected) {
    die ('Can\'t use sitename : ' . mysql_error());
}

// make sitename the current db
$db_selected = mysql_select_db('sitename', $link);
if (!$db_selected) {
    die ('Can\'t use sitename : ' . mysql_error());
}

// Make the query.
$query = "INSERT INTO users (first_name, last_name, email, password, registration_date) VALUES ('$fn', '$ln', '$e', SHA
('$p'), NOW() )";
$result = @mysql_query ($query); // Run the query.
if ($result) { // If it ran OK.

// Send an email, if desired.

// Print a message.
echo '<h1 id="mainhead">Thank you!</h1>
<p>You are now registered.  In Chapter 9 you will actually be able to log in!</p><p><br/></p>';

// Include the footer and quit the script (to not show the form).
include ('./footer.html');
exit();

} else { // If it did not run OK.
echo '<h1 id="mainhead">System Error</h1>
<p class="error">You could not be registered due to a system error.  We apologize for any inconvenience.</p>'; // Public message.
echo '<p>' . mysql_error() . '<br/><br/>Query: ' . $query . '</p>'; // Debugging message.
include ('./footer.html');
exit();
}

mysql_close(); // Close the database connection.

} else { // Report errors.

echo '<h1 id="mainhead">Error!</h1>
<p class="error">The following error(s) occurred:<br/>';
foreach ($errors as $msg) { // Print each error.
echo " - $msg<br/>\n";
}
echo '</p><p>Please try again</p><p><br/></p>';

} // End of if (empty($errors)) IF.

} // End of the main Submit conditional.
?>
<h2>Register</h2>
<form action="register.php" method="post">
<p>First Name: <input type="text" name="first_name" size="15" maxlength="15" value="<?php if (isset($_POST

['first_name'])) echo $_POST['first_name']; ?>" /></p>
<p>Last Name: <input type="text" name="last_name" size="15" maxlength="30" value="<?php if (isset($_POST['last_name'])) 

echo $_POST['last_name']; ?>" /></p>
<p>Email Address: <input type="text" name="email" size="20" maxlength="40" value"<?php if (isset($_POST['email'])) echo 

$_POST['email']; ?>" /></p>
<p>Password: <input type="password" name="password1" size="10" maxlength="20" /></p>
<p>Confirm Password: <input type="password" name="password2" size="10" maxlength="20" /></p>
<p><input type="submit" name="submit" value="Register" /></p>
<input type="hidden" name="submitted" value="TRUE" />
</form>
<?php
include ('./footer.html');
?>

 

 

Parse error:  parse error, expecting `','' or `';'' in C:\wamp\www\register.php on line 75

[btherl]

Ok there's a few problems there.  The indentation at the start should be

 

// Check if the form has been submitted.
if (isset($_POST['submitted'])) {
    $errors = array(); // Initialize error array.

    // Check for a first name.
    if (empty($_POST['first_name'])) {
        $errors[] = 'You forgot to enter your first name.';
    } else {
        $fn = trim($_POST['first_name']);
    }

 

And notice that there's no closing "}" on that first "if" - so php will be expecting it to be closed further down.

 

Second, there's a parse error:

 

echo // Already registered.

'<h1 id="mainhead">Error!</h1>
<p class="error">This email address has already been registered.</p>;
}

// make sitename the current db
$db_selected = mysql_select_db('sitename', $link);
if (!$db_selected) {
    die ('Can\'t use sitename : ' . mysql_error());
}

 

If you look at how phpfreaks highlights this, it looks odd.  It's because the closing quote (the ' character) is missing.  Try:

 

echo // Already registered.

'<h1 id="mainhead">Error!</h1>
<p class="error">This email address has already been registered.</p>';
}

// make sitename the current db
$db_selected = mysql_select_db('sitename', $link);
if (!$db_selected) {
    die ('Can\'t use sitename : ' . mysql_error());
}

[BrentonHale]

Thank you, the problem has been resolved! 

 

Thanks for being patient with me, I have less than two weeks experience with PHP coding.

[btherl]

No worries   I guessed from how you worded the first post that you're new to php.