I have trouble connecting to mysql - php

Question

I've created a database on az.pl I wanted to use old code which works perfectly on other website. I get this error message:
Could not connect to mysql
Here's my code:
$dbh = mysqli_connect("localhost","user","password", "db") or die ("could not connect to mysql");
I've also tried:
$c = mysql_connect("localhost", "user", "password");
mysql_select_db("db");
$result = mysql_query("SELECT 'Hello, dear MySQL user!' AS _message FROM DUAL");
$row = mysql_fetch_assoc($result);
echo htmlentities($row['_message']);
Both with the same result, the error message.
I've searched the web but I haven't found exact problem.

Answer 1

Consider following the docs when debugging your connection issue:
http://php.net/manual/en/function.mysqli-connect.php
<?php
$link = mysqli_connect("localhost", "user", "password", "db");
if (!$link) {
echo "Error: Unable to connect to MySQL." . PHP_EOL;
echo "Debugging errno: " . mysqli_connect_errno() . PHP_EOL;
// this will tell you why the connection failed
echo "Debugging error: " . mysqli_connect_error() . PHP_EOL;
exit;
}
echo "Success: A proper connection to MySQL was made! The my_db database is great." . PHP_EOL;
echo "Host information: " . mysqli_get_host_info($link) . PHP_EOL;
mysqli_close($link);
?>

Answer 2

I finally connected to the database. All I needed to do is to change isset to if in the following code:
if (!$_GET['pid']) {
$pageid = '1';
} else {
$pageid = ereg_replace("[^0-9]", "", $_GET['pid']); // filter everything but numbers for security
}
// Query the body section for the proper page
$sqlCommand = "SELECT pagebody FROM pages WHERE id='$pageid' LIMIT 1";
$query = mysqli_query($link, $sqlCommand) or die (mysqli_error());
while ($row = mysqli_fetch_array($query)) {
$body = $row["pagebody"];
}
I used MonkeyZeus code to connect to the database.Thank you MonkeyZeus.