SQL queries to another wordpress site

Question

I have 2 wordpress sites on the same hosting and the same host/user/ password for the database I have on the other hand 2 different database and 2 different prefixes I need, during an action on site1, to go and make requests on site2 (SELECT and after, UPDATE) I saw that we could do

$mydb = new wpdb('username','password','database','localhost');
$rows = $mydb->get_results("select Name from my_table");

But putting that in site1's functions.php file isn't very secure is it?

How to do this in a clean way and avoid any attempt to hack the database if you access the functions.php file

Answer 1

Putting an important credentials in functions.php is not a good idea. The better way is you can utilize WP REST API from your second site to handle GET and POST method for the data and using global $wpdb variable inside the code.

You can either create a custom endpoint for that by making a custom plugin or insert the code into functions.php. You may need to configure the permission_callback parameter for the API endpoint whether it is being used internally or publicly.

Read more on REST API Handbook