Why is the error Function name must be a string ???

Question

PHP

Swears at this line, what's the problem ???

$result = mysqli_query($connection,"SELECT * FROM cart,adidas WHERE cart.cart_ip = '{$_SERVER('REMOTE_ADDR')}' AND adidas.id = cart.cart_id_products");

Answer 1

$_SERVER('REMOTE_ADDR') -> $_SERVER['REMOTE_ADDR']

Answer 2

$_SERVER('REMOTE_ADDR')

You are trying to call a function. And $_SERVER is not a function and not something castable to a callable