What is servername - php

Question

i just wanted to insert data into database from a form, with php. i ran the code below in my Localhost using XAMPP and everything was fine but where i upload it to my host it didn't work.
Question is What shold i put for $servername and when should i look for it ?
There is my codes:
Register.php (in localhost)
<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "test";
$Name = $_POST['Name'];
$Username = $_POST['Username'];
$Password = $_POST['Password'];
$Email = $_POST['Email'];
// Create connection
$conn = mysqli_connect($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
header("Location:#");
}
//Inserting Data
try{
$sql = "INSERT INTO User (uName , uUsername , uPassword , uEmail) VALUES ('$Name' , '$Username' , '$Password' , '$Email')";
mysqli_query($conn, $sql);
}catch (Exception $e) {
echo 'Caught exception: ', $e->getMessage(), "\n";
}
$conn->close();
header("Location:#");
}
?>

Answer 1

If your MySQL database is on the SAME SERVER as your PHP script, then the usual logical approach is that your host is localhost. The same as you used on your local computer -- because they're on the same machine.
However, if your MySQL database is on ANOTHER SERVER seperate from your PHP scripts the you will need to access that server using a web address for your PHP to connect to yout MySQL.
We can't tell you what that is, and your server hosts (of your MySQL server) will be able to tell you and provide you with the correct login credentials.
I believe it would be more usual for MySQL and PHP to be on the same disk, especially for non-professional systems as your appears to be, so then the issue would be:
Are your login details set up correcty on your server? (same username/password)
Are there any MySQL errors or PDO errors (if you connect with PDO). Don't redirect on error, but instead output the error to a log file so you can read WHY the MySQL in your code didn't connect.
It is still possible for you to set your PHP to communicate with your localhost MySQL via a remote address (such as servername=$_SERVER['SERVER_NAME'];). (see note below)
Many online accounts (in things such as CPanel) will block you from accessing the MySQL as a root or at least will not give you the root MySQL password. Using root to access MySQL via PHP is NOT a good idea and you should instead set up a specific MySQL user for your PHP with only enough privileges that you need to read/write to the DB, and nothing more.
If your MySQL is remote (not localhost) then you may also need to supply a Port Number with the connection details. Usual port numbers are 3306 but this is something you'd need to know from your server hosts.
Immediately after a header(Location:); redirection instruction you should always set die(); or exit to stop PHP processing the rest of the script.
Your SQL insert data is highly suseptible to SQL injection and other SQL attacks and compromise. You should really, REALLY look into using MySQL Prepared Statements, you're already coding in OO style so you're almost there already.
Example remote connection from the manual
<?php
/***
* Remember 3306 is only the default port number, and it could be
* anything. Check with your server hosts.
***/
$conn = new mysqli('remote.addr.org.uk', 'username', 'my_password', 'my_databasa', '3306');
/***
* This is the "official" OO way to do it,
* BUT $connect_error was broken until PHP 5.2.9 and 5.3.0.
***/
if ($conn->connect_error) {
error_log('MySQL Connect Error (' . $conn->connect_errno . ') '
. $conn->connect_error);
}
/***
* Upon failure, the above will output a connection error notice such as
* user not found or password incorrect. It won't explicity say these
* things but you should be able to deduce which from the notice
***/
echo "Success... \n" . $conn->host_info ;
$mysqli->close();
# : I seem to think that MySQL detects when the remote address given is the same as the server address and auto converts it to localhost, but I'm not sure on this.
The long and the short of it is that if your MySQL is on the same
server as your PHP it makes no sense to open up a network loop to send
data out just to get it back again. Use localhost instead.

Answer 2

I asked my host service providers about the "$servername" and they answered me that the "$serverneme" is localhost.