PHP error message for required input field - php

Question

I am trying to display an error message if a user has not entered a email and not add a column to the table.
The php code sends the email & randomly generated Code to the database and then displays a message, but if their has been not been a email entered I am trying to get a message to ask for an email and not create a column until done so.
I have achieved this before with other data inputing but I am still new to PHP, I have checked for answers but cannot just find the simple fix which I know it is.
Any help or comments would be greatly appreciated, thanks (Y)
PHP:
<?php
if(!empty($_POST['email'])) {
?>
<p>Enter an email</p>
<?php
}
if(isset($_POST['send'])){
$email = mysqli_real_escape_string($conn,$_POST['email']);
$length = 10;
$inviteCode = "";
$characters = "0123456789abcdefghijklmnopqrstuvwxyz";
for ($p = 0; $p < $length; $p++) {
$inviteCode .= $characters[mt_rand(10, strlen($characters))];
}
$query = mysqli_query($conn, "INSERT INTO `referrals` (`email`, `inviteCode`)
VALUES ('$email', '$inviteCode') ");
if($query){
?>
<p> "Thank you"</p>
<?php
}
else{
?>
<p>Sorry there must have been a problem</p>
<?php
die('Error querying database. ' . mysqli_error($conn));
}
} // end brace for if(isset($_POST['Login']))
// end brace for if(isset($_POST['Login']))
?>
I have achieved this before by putting the following at the top;
if (empty($_POST) === false) {
$required_fields = array('email');
foreach($_POST as $key=>$value) {
if (empty($value) && in_array($key, $required_fields) === true) {
$errors[] = 'Please Enter All Information';
break 1;
}
}
}
The html code for the submit and email input tags are below:
<input type="text" placeholder="Email" name="email" />
<input type="submit" value="send" name="send" />

Answer 1

Add if(!empty($_POST['email'])) to the top of your logic, instead of isset($_POST['send']) unless you are doing something else with the post send value later in your logic. isset will be true if there is an empty string.
To understand why please see:
isset() and empty() - what to use
Edit:
<?php
if(!empty($_POST)){
if(!empty($_POST['email'])){
$email = mysqli_real_escape_string($conn,$_POST['email']);
$length = 10;
$inviteCode = "";
$characters = "0123456789abcdefghijklmnopqrstuvwxyz";
for ($p = 0; $p < $length; $p++) {
$inviteCode .= $characters[mt_rand(10, strlen($characters))];
}
$query = mysqli_query($conn, "INSERT INTO `referrals` (`email`, `inviteCode`) VALUES ('$email', '$inviteCode') ");
//you might want to consider checking more here such as $query == true as it can return other statuses that you may not want
if($query){
?>
<p> "Thank you"</p>
<?php
}
else{
?>
<p>Sorry there must have been a problem</p>
<?php
die('Error querying database. ' . mysqli_error($conn));
}
}
else {
?>
<p>Enter an email</p>
<?php
}
}
?>

Answer 2

Try this:
<?php
// check if email is empty, if it is display this message
if(empty($_POST['email'])) {
?>
<p>Enter an email</p>
<?php
}
// else: the user entered something
else {
$email = mysqli_real_escape_string($conn,$_POST['email']);
$length = 10;
$inviteCode = "";
$characters = "0123456789abcdefghijklmnopqrstuvwxyz";
for ($p = 0; $p < $length; $p++) {
$inviteCode .= $characters[mt_rand(10, strlen($characters))];
}
$query = mysqli_query($conn, "INSERT INTO `referrals` (`email`, `inviteCode`)
VALUES ('$email', '$inviteCode') ");
if($query){
?>
<p> "Thank you"</p>
<?php
}
else {
?>
<p>Sorry there must have been a problem</p>
<?php
die('Error querying database. ' . mysqli_error($conn));
} // end else
} // end else
?>