Question

The following basic code is working as expected.

<?php
mysql_connect("localhost", "user", "user@123") or die(mysql_error());
echo "Connected to MySQL<br />";
?>

What all I need is that instead of mysql_error, page not found 404 error should be returned.
I am looking for the shortest possible code since this is going to be used as load balancer check.

The following does not seem to work. I get a blank page.

mysql_connect("localhost", "user", "user@123") or die(header("HTTP/1.0 404 Not Found"));

Answer 1

I would do the following: bearing in mind I am using mysqli instead, the use of mysql_* is highly discouraged.

$mysqli = new mysqli('localhost', 'user', 'password', 'dbname');

if ($mysqli->connect_error) {
    header("HTTP/1.0 404 Not Found");
} else {

}

Are you sure you want to return a 404 though, this is misleading as the resource has been found, I would be returning a 500 error as a server error which would be more appropriate.

For a list of HTTP status codes see here