sending an email based on data from MySQL table - php

Question

I've got email function setup and working by setting the code to email a specific email address. However, with this is that it goes to the same email address everytime the submit button is pressed based on the data entered in a text box who the mail comes from.
However, I want to change it so that when a user enters their username in the username box it checks my database table for that username and checks their email address and emails them all the information set for that user.
The code i'm using is ;
$username = $_POST['username'];
$my_query="SELECT * from loanusers where username = '$username'";
$result= mysqli_query($connection, $my_query);
$to = $myrow["emailaddess"];
$subject = 'CSG - Forgotten Password';
$sender = 'CSGLoanSystem#mail.com';
$password = $myrow["password"];
$admin = 'CSGLoanSystem Admin Team';
$body = <<< EMAIL
Hi {$username}, You have recently requested a notification of your password.
The Password registered with account {$username} is $password.
Thanks - {$admin}
EMAIL;
$header = "From:" . $sender;
if ($result):
mail($to, $subject, $body, $header);
$feedback = 'Email Sent';
endif;
At the moment when the submit button is pressed, the page refreshes but nothing actually happens and no email is received at the expected email address?

Answer 1

Pointing to the right direction:
Read up on MySQL and PDO. Also Read up on prepared statements and parameter binding.
Elaborating on the directions given:
There are many ways to connect to a database, and there are many different databases available. One popular database software is called MySQL, and the coding method that is most recommended to connect to that database is PDO for reasons such as having better methods for preventing security breaches.
You can find a lot of online tutorials on how to connect to a database, so I won't go into that, though I will however give you an example of a query you could use to do your email searching, and also I'll include prepared statements and parameter binding since these two details are often misunderstood by a lot of programmers.
If you have the following table:
users
______________________________
| username | email |
|------------+-----------------|
| john44 | abc#gmail.com |
|------------+-----------------|
| adam11 | 123#gmail.com |
|------------+-----------------|
the following code would allow you to retrieve john44's email:
$username = $_POST['username'];//getting the username written in the form
$sql = "SELECT email FROM users WHERE username = ?";
$stmt = $conn->prepare($sql);
$stmt->execute([$username]);
$result = $stmt->fetch(PDO::FETCH_ASSOC);
//here I'm just outputting the obtained email for you to see
//it works, however you would then use the email saved in
//$result['email'] whichever way you want.
echo "email = {$result['email']}<br>";
Edited:
After you edited your code, I noticed you are not fetching the information you queried. Insert the following code after line $result= mysqli_query($connection, $my_query);:
$myrow = mysqli_fetch_assoc($result);