如何在If条件中添加两个表？

Can someone help me in this simple code? (Unfortunately, I don't have experience in programming)

I want to add two tables inside if condition.

Here my code:

if($n_name == '') {
    echo "<div class='alert alert-error'>All options are required!</div>";
}

I've done like this:

if($n_name, $n_city == '') {
    echo "<div class='alert alert-error'>All options are required!</div>";
}

but didn't work!

Try with &:

if($n_name & $n_city == '') {
    echo"<div class='alert alert-error'>All options are required!</div>";
}