Can not connect to my database server using PHP - php

Question

I'm trying to build a profile page system for users bare in mind I'm real new to php. In the code below, I get the error message I specified it to echo, when i cannot connect to my database ie :
"could not connect to server"
I dont get any other error messages, only this. I cant seem to find the problem, any help would be appreciated.
Here is my code :
<?php
include_once 'Header.php';
?>
<?php
if (isset($_GET['user_uid']))
$user_uid = $_GET['user_uid'];
mysqli_connect($dbServername, $dbUsername, $dbPassword, $dbName);
mysqli_select_db($conn, "users") or die ("could not connect to server");
$userquery = mysqli_query("SELECT * FROM users where user_uid='$user_uid'")
or die ("The Query could not be completed, contact an administrator");
if (mysql_num_rows($userquery) != 1) {
die ("that username could not be found");
}
while ($row = mysqli_fetch_array($userquery, MYSQL_ASSOC)) {
$first = $row['first'];
$last = $row['last'];
$city = $row['city'];
$country = $row['country'];
}
?>
<table width="398" border="0" align="center" cellpadding="0">
<tr>
<td height="26" colspan="2">Your Profile Information </td>
<td><div align="right">logout</div></td>
</tr>
<?php echo $first; ?>
<tr>
<td width="129" rowspan="5"><img src="<?php echo $picture ?>" width="129"
height="129" alt="no image found"/></td>
<td width="82" valign="top"><div align="left">FirstName:</div></td>
<td width="165" valign="top"><?php echo $first ?></td>
</tr>
<tr>
<td valign="top"><div align="left">LastName:</div></td>
<td valign="top"><?php echo $last ?></td>
</tr>
<tr>
<tr>
<td valign="top"><div align="left">City:</div></td>
<td valign="top"><?php echo $city ?></td>
</tr>
<tr>
<td valign="top"><div align="left">Country:</div></td>
<td valign="top"><?php echo $country ?></td>
</tr>
</table>
<p align="center"></p>
<?php
include_once 'Footer.php';
?>

Answer 1

It is specifically dying because of $conn - that doesn't appear to be set anywhere.
However in saying that, as has been pointed out, you don't need to use mysqli_select_db in mysqli as it's all done in the mysqli_connect function.
$conn = mysqli_connect($dbServername, $dbUsername, $dbPassword, $dbName);
That is enough - you only need the mysqli_db to change the current DB, but even then it needs a valid link identifier (the result returned by mysqli_connect).
So, that would be:
mysqli_select_db($conn, "users") or die ("could not connect to server");
...as long as $conn is valid.

Answer 2

Sorry guys, the whole layout I was using was wrong, for making a live profile page, this new layout fixed the problems :)...
<?php
include_once 'RoadieHeader.php';
?>
<?php
//PULLING OUT USERNAME//
$result = mysqli_query($conn, "select user_uid from users where user_uid
='".$_SESSION['u_uid']."'");
$row = mysqli_fetch_array($result);
$uid = ucfirst($row['user_uid']);
//PULLING OUT EVERYTHING!//
$result_f = mysqli_query($conn, "select user_first from users where
user_first ='".$_SESSION['u_first']."'");
$row_f = mysqli_fetch_array($result_f);
$first = ucfirst($row_f['user_first']);
$last = ucfirst($_SESSION['u_last']);
$city = ucfirst($_SESSION['u_city']);
$country = ucfirst($_SESSION['u_country']);
$about = ucfirst($_SESSION['u_about']);
?>
<table width="398" border="0" align="center" cellpadding="0">
<tr>
<td height="26" colspan="2"><?php echo $uid ?></td>
<td><div align="right">logout</div></td>
</tr>
<tr>
<td width="129" rowspan="5"><img src="<?php echo $picture ?>"
width="129" height="129" alt="no image found"/></td>
<td width="82" valign="top"><div align="left">FirstName:</div></td>
<td width="165" valign="top"><?php echo $first ?></td>
</tr>
<tr>
<td valign="top"><div align="left">LastName:</div></td>
<td valign="top"><?php echo $last ?></td>
</tr>
<tr>
<tr>
<td valign="top"><div align="left">City:</div></td>
<td valign="top"><?php echo $city ?></td>
</tr>
<tr>
<td valign="top"><div align="left">Country:</div></td>
<td valign="top"><?php echo $country ?></td>
</tr>
<tr>
<td valign="top"><div align="left">About me: </div></td>
<td valign="top">
<?php echo $about ?>
</td>
</tr>
</table>
<p align="center"></p>
<?php
include_once 'RoadieFooter.php';
?>
I forgot the current user's ID's are stored in $_SESSION when they log in, and is carried page to page on session_start()