Cannot get php to successfully query mysql - what am I doing wrong?

Website Building
#1

I’m running the following code from a very basic php script, and it is not able to connect to the mysql database:

		<?
		mysqli_connect(Constants::DB_HOST,Constants::DB_USERNAME,Constants::DB_PASSWORD,Constants::DB_DATABASE) or die (mysqli_error());
		
		$sql	 = mysqli_query("SELECT * FROM 'owners'"); 
		while($row = mysqli_fetch_assoc($sql))
		{ ?>
		<p><?=$row["id"];?></p>
		<? } ?>

I’m using “localhost” for the host (as instructed on the Database page in my Manage Databases page. Username, password and database are all correct, and are echoed elsewhere on my page to ensure they’re working.

What am I doing wrong here?

#2

open database:

$db_hostname = 'localhost';
$db_username = 'id00000_name';
$db_password = 'password';
$db_database = 'id00000_main';
$con = new mysqli($db_hostname,$db_username,$db_password,$db_database);
if ($con->connect_error)
{
    		die('Could not connect: ' . $con->connect_error);
}

execute query:

$sql="SELECT * FROM 'TABLE';";
$result=$con->query($sql);
while($row=$result->fetch_assoc())
{
    //print stuff
}

if i were you, i’d make the open database part into a function:
openDB.php:

<?php
function openDB(){
    $db_hostname = 'localhost';
    $db_username = 'id00000_name';
    $db_password = 'password';
    $db_database = 'id00000_main';
    $con = new mysqli($db_hostname,$db_username,$db_password,$db_database);
    if ($con->connect_error)
    {
 	die('Could not connect: ' . $con->connect_error);
    }
    return $con;
}
?>

yourfile.php:

<?php
include 'openDB.php';
$con=openDB();
//execute query as per above
?>
#3

always use full php tags <?php and never use <?

#5