How to check if mysqli_connect was successful or n

问题:

I'm writing an installer script and I need to check if the user entered correct database information and therefore need to check if mysqli_connect was successful or not. A simple if-else will suffice.

回答1:

Like so:

if( ! $db = mysqli_connect(...) ) {
    die('No connection: ' . mysqli_connect_error());
}

回答2:

What about this:

<?php
$con = mysqli_connect("localhost","my_user","my_password","my_db");

// Check connection
if (mysqli_connect_errno())
    {
    echo "Failed to connect to MySQL: " . mysqli_connect_error();
    }
?>