PHP: Check if email already exists when running this code - php

Question

I have built a very simple PHP form that allows a user to send an application using the following PHP code:
if($_SERVER['REQUEST_METHOD'] == 'POST')
{
$host = '###';
$username = '###';
$pass = '###';
mysql_connect($host,$username,$pass);
mysql_select_db("###");
$status = mysql_real_escape_string($_POST['status']);
$firstname = mysql_real_escape_string($_POST['firstname']);
$lastname = mysql_real_escape_string($_POST['lastname']);
$email = mysql_real_escape_string($_POST['email']);
$url = mysql_real_escape_string($_POST['url']);
$query = "INSERT INTO creathive_applications
VALUES (NULL,'$status','$firstname','$lastname','$email','$url')";
$result = mysql_query($query) or trigger_error(mysql_error().". Query: ".$query);
}
What I want to do is make sure that the same person doesn't apply TWICE so if the email address already exists in the database then it will show a message on the form saying "sorry looks like you've already applied".
Here is the HTML form, and I have added the message inside the fieldset, so need to do a) show this message if the email exits or show success message and then b) add #membership form to the url to make the view jump to form on the page so that the user will see the messages. Can any help with this? THANKS
<form action="" method="post">
<fieldset id="membershipform">
<div id="error"><p>sorry email in use</p></div>
<div id="success"><p>Thanks your application has been sent</p></div>
<ul class="clearfix">
<li id="li-status">
<span>I am a:</span>
<menu>
<li><label for="student"><input type="radio" name="status" id="student" checked="checked" value="Graduate" /> Graduate</label></li>
<li><label for="student2"><input type="radio" name="status" id="student2" value="Undergraduate" /> Undergraduate</label></li>
</menu>
</li>
<li id="li-firstname">
<label for="firstname">First Name</label> <input name="firstname" type="text" placeholder="First Name" id="firstname" title="First Name" />
</li>
<li id="li-lastname">
<label for="lastname">Last Name</label> <input name="lastname" type="text" placeholder="Last Name" id="lastname" title="Last Name" />
</li>
<li id="li-email">
<label for="email">Email address</label> <input name="email" type="text" placeholder="Email address" id="email" title="Email address" />
</li>
<li id="li-url">
<label for="url">URL</label> <input name="url" type="text" placeholder="URL of something you've made" id="url" title="URL of something you've made" />
</li>
<li id="li-buttons">
<input name="submit" type="submit" value="Send Application ►" title="Send Application" />
</li>
</ui>
</fieldset>
</form>

Answer 1

Do a select query before insert to validate there aren't any entries for the email already:
select from creathive_applications where email = $email
If any results come back, then display your message instead of inserting the record. You can add javascript onload code to move form to #membershipform if the email already existed.

Answer 2

You can alter table so that email id is primary so it will be unique.
You can check with another query
select from creathive_applications where emai='$email'

Answer 3

simple , you must check it agains your database .
if($_SERVER['REQUEST_METHOD'] == 'POST'){
$host = '###';
$username = '###';
$pass = '###';
mysql_connect($host,$username,$pass);
mysql_select_db("###");
$status = mysql_real_escape_string($_POST['status']);
$firstname = mysql_real_escape_string($_POST['firstname']);
$lastname = mysql_real_escape_string($_POST['lastname']);
$email = mysql_real_escape_string($_POST['email']);
$url = mysql_real_escape_string($_POST['url']);
$query_check = "SELECT COUNT(*) as existents FROM creathive_applications .... emailfiel = 'email_entered'";
switch($query_check['existents']){
case 0:
//do the insert operation
$query = "INSERT INTO creathive_applications VALUES (NULL,'$status','$firstname','$lastname','$email','$url')";
$result = mysql_query($query) or trigger_error(mysql_error().". Query: ".$query);
break;
default:
echo "no no";
}
}

Answer 4

Check if $email exists in your DB and if it does set $error = 1. Then if $error = 1, print the message.
$emailchk = mysql_query("SELECT * FROM creathive_applications WHERE email = '$email'");
if(mysql_num_rows($emailchk) > 0) {
$error = 1;
}
if isset($error) {
echo '<div id="error"><p>sorry email in use</p></div>';
}

Answer 5

You could do it like this:
PHP Code:
if($_SERVER['REQUEST_METHOD'] == 'POST')
{
$host = '###';
$username = '###';
$pass = '###';
$emailerror = null;
mysql_connect($host,$username,$pass);
mysql_select_db("###");
$status = mysql_real_escape_string($_POST['status']);
$firstname = mysql_real_escape_string($_POST['firstname']);
$lastname = mysql_real_escape_string($_POST['lastname']);
$email = mysql_real_escape_string($_POST['email']);
$url = mysql_real_escape_string($_POST['url']);
$emailchk = mysql_query("SELECT * FROM creathive_applications WHERE email = '$email'");
if(mysql_num_rows($emailchk) == 0) {
$query = "INSERT INTO creathive_applications VALUES (NULL,'$status','$firstname','$lastname','$email','$url')";
$result = mysql_query($query) or trigger_error(mysql_error().". Query: ".$query);
}else{
$emailerror = '<span style="color:rgb(255,0,0)">Email already taken</span>';
}
}
HTML (Must be in the same file):
<form action="" method="post">
<fieldset id="membershipform">
<div id="error"><p>sorry email in use</p></div>
<div id="success"><p>Thanks your application has been sent</p></div>
<ul class="clearfix">
<li id="li-status">
<span>I am a:</span>
<menu>
<li><label for="student"><input type="radio" name="status" id="student" checked="checked" value="Graduate" /> Graduate</label></li>
<li><label for="student2"><input type="radio" name="status" id="student2" value="Undergraduate" /> Undergraduate</label></li>
</menu>
</li>
<li id="li-firstname">
<label for="firstname">First Name</label> <input name="firstname" type="text" placeholder="First Name" id="firstname" title="First Name" />
</li>
<li id="li-lastname">
<label for="lastname">Last Name</label> <input name="lastname" type="text" placeholder="Last Name" id="lastname" title="Last Name" />
</li>
<li id="li-email">
<label for="email">Email address</label> <input name="email" type="text" placeholder="Email address" id="email" title="Email address" /> <?php echo $emailerror;?>
</li>
<li id="li-url">
<label for="url">URL</label> <input name="url" type="text" placeholder="URL of something you've made" id="url" title="URL of something you've made" />
</li>
<li id="li-buttons">
<input name="submit" type="submit" value="Send Application ►" title="Send Application" />
</li>
</ui>
</fieldset>
</form>