Connecting to a remote mysql server using a function - php

Question

I'm using wordpress and I have a remote mysql server for some other data not stored on wordpress db.
Now I want to connect to that remote mysql server in a form of a php function but i don't know how or if it is possible. Basically this function serves as to check if $orderid exist on the remote mysql server.
function check_orderid($orderid) {
// Connect to database
// Check if $orderid exist if yes return true.
}
The remote server does accept remote connections.
Also, Is it okay and will not affect wordpress db connection?

Answer 1

Connecting to a remote server is not different from connecting to a local server, besides the host address. Just replace the 'localhost' with a resolvable dns name, or the ip address from your remote server, and you should be fine.

Answer 2

To make multiple connection you have to use links.
they are created after successful connect:
$link1 = mysqli_connect('localhost', 'my_user', 'my_password', 'my_db');
$link2 = mysqli_connect('localhost', 'my_user2', 'my_password2', 'my_db2');
you can use them like:
mysqli_query($link1, "your first query as string");
mysqli_query($link2, "your second query as string");
By official OO version you should use:
$mysqli1 = new mysqli('localhost', 'my_user', 'my_password', 'my_db');
$mysqli2 = new mysqli('externalIP', 'my_user2', 'my_password2', 'my_db2');
$mysqli1->query("some query");
$mysqli1->query("some other query");
so, in this case you can easily do this:
$externaldbcon = new mysqli('ExtrnalDBIP', 'my_user', 'my_password', 'my_db');
$externaldbcon->query("your query for external DB");