PHP - Oop In Php Using Mysqli Connection

Hi,

3 different tutorials teach 3 different ways on how to get php mysqli echo connection errors.

Which one should I memorise out of these 3 you advise ?
I'd like your rankings on these 3 atleast ....

1.
https://www.php.net/manual/en/function.mysqli-connect.php

$link = mysqli_connect("127.0.0.1", "my_user", "my_password", "my_db");
	if (!$link) {
    echo "Error: Unable to connect to MySQL." . PHP_EOL;
    echo "Debugging errno: " . mysqli_connect_errno() . PHP_EOL;
    echo "Debugging error: " . mysqli_connect_error() . PHP_EOL;
    exit;
}
mysqli_close($link);

2.
https://www.tutorialrepublic.com/php-tutorial/php-mysql-connect.php

$link = mysqli_connect("localhost", "root", "");
 
// Check connection
if($link === false){
    die("ERROR: Could not connect. " . mysqli_connect_error());
}
 
// Print host information
echo "Connect Successfully. Host info: " . mysqli_get_host_info($link);
 
// Close connection
mysqli_close($link);

3.
https://www.geeksforgeeks.org/php-mysqli_connect-function/

    mysqli_connect("localhost", "root", "", "GFG");
 
    if(mysqli_connect_error())
        echo "Connection Error.";
    else
        echo "Database Connection Successfully.";

Q2. On the connection point check, you give your rankings on these following 3 based on your preference.
I ranked like this:

A.

 if(mysqli_connect_error())

B.

if($link === false){

C.

if (!$link) {

Q3. On the connection error reporting point (error message echoing point), you give your rankings on these following 3 based on your preference.
I ranked like this:

A.

die("ERROR: Could not connect. " . mysqli_connect_error());

B.

echo "Connection Error.";

C.

    echo "Debugging errno: " . mysqli_connect_errno() . PHP_EOL;
    echo "Debugging error: " . mysqli_connect_error() . PHP_EOL;

Briefly, let me know:

A). Which connection error checking point to use and which error message echoing point to use.

B). If you got your own that is better and more helpful then explain why it is better over these 3 and any others.

Hey Guys, So I am working on implementing zip codes to my database. I found a zip code calculator script, and I am forced to pass the database connection to the class. Although, I realize I use a mysqli connection and the zipcodes class uses mysql...

Appreciate if anyone could assist me in solving my issue. THANKS!

ERRORS...
Quote

Warning: mysql_query(): supplied argument is not a valid MySQL-Link resource in /home/bleeping/public_html/gregstechservices.com/gregphp/ZipCodesRange.class.php on line 287

Warning: mysql_errno(): supplied argument is not a valid MySQL-Link resource in /home/bleeping/public_html/gregstechservices.com/gregphp/ZipCodesRange.class.php on line 289

Warning: mysql_error(): supplied argument is not a valid MySQL-Link resource in /home/bleeping/public_html/gregstechservices.com/gregphp/ZipCodesRange.class.php on line 289
MySql Error #:



zip.php
<?php 
require_once("class/mysql_connect.php");
$mysql = New MySQL();
require_once("ZipCodesRange.class.php");
//initialization, pass in DB connection, from zip code, distance in miles.
$zip = new ZipCodesRange($mysql,'98303',50);

//configuration
$zip->setTableName('zipcodes'); //optional, default is zips.
$zip->setZipColumn('ZipCode'); //optional, default is zip.
$zip->setLonColumn('Longitude'); //optional, default is lon.
$zip->setLatColumn('Latitude'); //optional, default is lat.

//do the work
$zip->setZipCodesInRange(); //call to initialize zip array

//zip code output, other processing can be done from this array.
$zipArray = $zip->getZipCodesInRange();

echo '<pre>';
print_r($zipArray);
echo '</pre>';

?>

mysql_connect.php

<?php

require_once ("includes/constants.php");
class MySQL
{

    private $conn;

    /**
     * MySQL::__construct()
     * 
     * @return
     */
    function __construct()
    {
        $this->conn = new mysqli(DB_SERVER, DB_USER, DB_PASS, DB_NAME) or die("Problem connecting to database");
        $dbc = $this->conn;
    }


    /*
    * Query the database
    * Example: $result = $mysql->query($q);
    */
    /**
     * MySQL::query()
     * 
     * @param mixed $q
     * @return
     */
    function query($q)
    {
        return $this->conn->query($q);
    }

...CONTINUED


ZipCodesRange.class.php

<?php
/**
 * Class to find zip codes within an approximate
 * distance of another zip code. This can be useful
 * when trying to find retailers within a certain
 * number of miles to a customer.
 *
 * This class makes some assumptions that I consider
 * pretty safe.  First it assumes there is a database
 * that houses all of the zip code information. 
 * Secondly it assumes there is a way to validate a
 * zip code for a given country.  It makes one bad
 * assumption and that is that the world is flat. See
 * comments below for an explanation.
 *
 * @author  Scott Mattocks
 * @created 2004-05-03
 * @updated 2004-05-14
 * @updated 2006-05-22 - MySQL Conversion by Allan Bogh
 * - Added precisionDistance() function to make calculations
 * more accurate (within 2 miles).
 * - Modified class initialization to make custom database settings
 * more effective.
 * New initialization steps:
 * $zip = new ZipCodesRange($appconf['dbconnection'],'98303',50);
 * $zip->setTableName('zip_codes'); //optional
 * $zip->setZipColumn('zip'); //optional
 * $zip->setLonColumn('longitude'); //optional
 * $zip->setLatColumn('latitude'); //optional
 * $zip->setZipCodesInRange(); //call to initialize zip array
 * echo '<pre>';
 * print_r($zip->getZipCodesInRange());
 * echo '</pre>';
 */

class ZipCodesRange {

  /**
   * The conversion factor to go from miles to degrees.
   * @var float
   */
  var $milesToDegrees = .01445;
  /**
   * The zipcode we are starting from.
   * @var string
   */
  var $zipCode;
  /**
   * The maximum distance in miles to return results for.
   * @var float
   */
  var $range;
  /**
   * The country the zip code is in.
   * @var string Two character ISO code.
   */
  var $country;  
  /**
   * The result of our search.
   * array(zip1 => distance, zip2 =>distance,...)
   * @var array
   */
  var $zipCodes = array ();
  /**
   * The database table to look for zipcodes in.
   * @var string
   */
  var $dbTable = 'zips';
  /**
   * The name of the column containing the zip code.
   * @var string
   */
  var $dbZip = 'zip';
  /**
   * The name of the column containing the longitude.
   * @var string
   */
  var $dbLon = 'lon';
  /**
   * The name of the column containing the latitude.
   * @var string
   */
  var $dbLat = 'lat';
  
  var $db;

  /**
   * Constructor. Calls initialization method.
   *
   * @access private
   * @param  resource $db The link identifier for the database.
   * @param  string  $zipCode
   * @param  float   $range
   * @param  string  $country Optional. Defaults to US.
   * @return object
   */
  function ZipCodesRange($db, $zipCode, $range, $country = 'US') {
    
    $this->_initialize($db, $zipCode, $range, $country);
  }

  /**
   * Initialization method. 
   * Checks data and sets member variables.
   *
   * @access private
   * @param  resource $db The link identifier for the database.
   * @param  string  $zipCode
   * @param  float   $range
   * @param  string  $country Optional. Defaults to US.
   * @return boolean 
   */   
  function _initialize($db, $zipCode, $range, $country) {
    //set up the database connection
$this->db = $db;

    // Check the country.
    if ($this->validateCountry($country)) {
      $this->country = $country;
    } else {
      trigger_error('Invalid country: ' . $country);
      return FALSE;
    }

    // Check the zipcode.
    if ($this->validateZipCode($zipCode, $country)) {
      $this->zipCode = $zipCode;
    } else {
      trigger_error('Invalid zip code: ' . $zipCode);
      return FALSE;
    }

    // We don't need a special method to check the range.
    if (is_numeric($range) && $range >= 0) {
      $this->range = $range;
    } else {
      trigger_error('Invalid range: ' . $range);
      return FALSE;
    }

    // Set up the zip codes.
    //return $this->setZipCodesInRange();
  }

  /**
   * Get all of the zip codes from the database.
   * Currently this method is called on construction but
   * it doesn't have to be.
   *
   * @access public
   * @return boolean
   */
  function setZipCodesInRange() {
    
    // First check that everything is set.
    if (!isset($this->zipCode) || !isset($this->range) || !isset($this->country)) {
      trigger_error('Cannot get zip codes. Class not initialized properly.');
      return FALSE;
    }

    // Get the max longitude and latitude of the starting point.
    $maxCoords = $this->getRangeBox();
    
    // The query.
    $query = 'SELECT ' . $this->dbZip . ', ' . $this->dbLat . ', ';
    $query.=  $this->dbLon . ' ';
    $query.= 'FROM ' . $this->dbTable . ' ';
    $query.= ' WHERE ';
    $query.= '  (' . $this->dbLat . ' <= ' . $maxCoords['max_lat'] . ' ';
    $query.= '    AND ';
    $query.= '   ' . $this->dbLat . ' >= ' . $maxCoords['min_lat'] . ') ';
    $query.= '  AND ';
    $query.= '  (' . $this->dbLon . ' <= ' . $maxCoords['max_lon'] . ' ';
    $query.= '    AND ';
    $query.= '   ' . $this->dbLon . ' >= ' . $maxCoords['min_lon'] . ') ';

    // Query the database.
    $qry = mysql_query($query,$this->db);
    
    // Check for errors.
    if (!$qry) {
      trigger_error('MySQL Error #'.mysql_errno($this->db).': '.mysql_error($this->db), E_USER_ERROR);
    }

    // Process each row.
    while ($result = mysql_fetch_array($qry)) {

      // Get the distance form the origin (imperfect see below).
      $distance = $this->precisionDistance($result[$this->dbLat], $result[$this->dbLon]);
      // Double check that the distance is within the range.
      if ($distance < $this->range) {
// Add the zip to the array
$this->zipCodes[$result[$this->dbZip]] = $distance;
      }
    }
    return TRUE;
  }

  /**
   * Return the array of results.
   *
   * @access public
   * @param  none
   * @return &array
   */
  function &getZipCodesInRange() {
    return $this->zipCodes;
  }

  /**
   * Calculate the distance from the coordinates are from the
   * origin zip code.
   *
   * The method is quite imperfect.  It assumes as flat Earth.
   * The values are quite accurate (depending on the conversion
   * factor used) for zip codes close  to the equator. I found
   * some crazy formula for calulating distance on a sphere
   * but I am not good enough at calculus to convert that into
   * working code.
   *
   * @access public
   * @param  float $lat       The latitude you want to know the distance to.
   * @param  float $lon       The longitude you want to know the distance to.
   * @param  float $zip       The zip code you want to know the distance from.
   * @param  int   $percision The number of decimals places in the distance.
   * @return float            The distance from the zip code to the coordinates.
   */
  function calculateDistance($lat, $lon, $zip = NULL, $percision = 2) {
    
    // Check the zip first.
    if (!isset ($zip)) {
      // Make it default to the origin zip code.
      // Could be used to calculate distances from other points.
      $zip = $this->zipCode;
    }
    // Get the coordinates of our starting zip code.
    list ($starting_lon, $starting_lat) = $this->getLonLat($zip);

    // Get the difference in miles for both coordinates.
    $diffLonMiles = ($starting_lon - $lon) / $this->milesToDegrees;
    $diffLatMiles = ($starting_lat - $lat) / $this->milesToDegrees;
    
    // Calculate the distance between two points.
    $distance = sqrt(($diffLonMiles * $diffLonMiles) + ($diffLatMiles * $diffLatMiles));

    // Return the distance rounded to the defined percision.
    return round($distance, $percision);
  }
  
  /**
   * See the report for calculateDistance function.
   */
  function precisionDistance($lat, $lon, $zip = NULL, $precision = 2){
   $earthsradius = 3963.19;
// Check the zip first.
    if (!isset ($zip)) {
      // Make it default to the origin zip code.
      // Could be used to calculate distances from other points.
      $zip = $this->zipCode;
    }

// Get the coordinates of our starting zip code.
    list ($starting_lon, $starting_lat) = $this->getLonLat($zip);
$pi = pi();
   $c = sin($starting_lat/(180/$pi)) * sin($lat/(180/$pi)) +
     cos($starting_lat/(180/$pi)) * cos($lat/(180/$pi)) *
        cos($lon/(180/$pi) - $starting_lon/(180/$pi));

$distance = $earthsradius * acos($c);
return round($distance,$precision);
  }

  /**
   * Get the longitude and latitude for a single zip code.
   *
   * @access public
   * @param  string $zip  The zipcode to get the coordinates for.
   * @return array  Numerically index with longitude first.
   */
  function getLonLat($zip) {
    
    // Get the longitude and latitude for the zip code.
    $query = 'SELECT ' . $this->dbLon . ', ' . $this->dbLat . ' ';
    $query.= 'FROM ' . $this->dbTable . ' ';
    $query.= 'WHERE ' . $this->dbZip . ' = \'' . addslashes($zip) . '\' ';

$qry = mysql_query($query,$this->db);
if(!$qry){
echo "MySql Error #".mysql_errno($this->db).': '.mysql_error($this->db).'<br>';
die;
}
    return mysql_fetch_array($qry);
  }

  /**
   * Check to see if the country is valid.
   *
   * Not implemented in any useful manner.
   *
   * @access public
   * @param  string  $country The country to check.
   * @return boolean
   */
  function validateCountry($country) {

    return (strlen($country) == 2);
  }

  /**
   * Check to see if a zip code is valid.
   *
   * Not implemented in any useful manner.
   *
   * @access public
   * @param  string $zip     The code to validate.
   * @param  string $country The country the zip code is in.
   * @return boolean
   */
  function validateZipCode($zip, $country = NULL) {
    
    // Set the country if we need to.
    if (!isset($country)) {
      $country = $this->country;
    }
    
    // There should be a way to check the zip code for every
    // acceptabe country.
    return TRUE;
  }

  /**
   * Get the maximum and minimum longitude and latitude values
   * that our zip codes can be in.
   *
   * Not all zipcodes in this box will be with in the range.
   * The closest edge of this box is exactly range miles away
   * from the origin but the corners are sqrt(2(range^2)) miles
   * away. That is why we have to double check the ranges.
   *
   * @access public
   * @param  none
   * @return &array The edges of the box.
   */
  function &getRangeBox() {

    // Calculate the degree range using the mile range
    $degrees = $this->range * $this->milesToDegrees;

    // Get the coords for our starting zip code.
    list($starting_lon, $starting_lat) = $this->getLonLat($this->zipCode);
    
    // Set up an array to return.
    $ret_array = array ();

    // Lat/Lon ranges 
    $ret_array['max_lat'] = $starting_lat + $degrees;
    $ret_array['max_lon'] = $starting_lon + $degrees;
    $ret_array['min_lat'] = $starting_lat - $degrees;
    $ret_array['min_lon'] = $starting_lon - $degrees;

    return $ret_array;
  }

  /**
   * Allow users to set the name of the database table holding
   * the information.
   *
   * @access public
   * @param  string $table The name of the db table.
   * @return void
   */
  function setTableName($table) {
    $this->dbTable = $table;
  }

  /**
   * Allow users to set the name of the column holding the
   * latitude value.
   *
   * @access public
   * @param  string $lat The name of the column.
   * @return void
   */
  function setLatColumn($lat) {
    $this->dbLat = $lat;
  }

  /**
   * Allow users to set the name of the column holding the
   * longitude value.
   *
   * @access public
   * @param  string $lon The name of the column.
   * @return void
   */
  function setLonColumn($lon) {
    $this->dbLon = $lon;
  }

  /**
   * Allow users to set the name of the column holding the
   * zip code value.
   *
   * @access public
   * @param  string $zips The name of the column.
   * @return void
   */
  function setZipColumn($zip) {
    $this->dbZip = $zip;
  }

  /**
   * Set a new origin and re-get the data.
   *
   * @access public
   * @param  string $zip The new origin.
   * @return void
   */
  function setNewOrigin($zip) {
    
    if ($this->validateZipCode($zip)) {
      $this->zipCode = $zip;
      $this->setZipCodesInRange();
    }
  }
  
  /**
   * Set a new range and re-get the data.
   *
   * @access public
   * @param  float  $range The new range.
   * @return void
   */
  function setNewRange($range) {
    
    if (is_numeric($range)) {
      $this->range = $range;
      $this->setZipCodesInRange();
    }
  }

  /**
   * Set a new country but don't re-get the data.
   * 
   * It isn't any good to check a zip code in two 
   * countries cause the rules for zip codes vary from
   * country to country.
   *
   * @access public
   * @param  string $country The new country.
   * @return void
   */
  function setNewCountry($coutry) {

    if ($this->validateCountry($country)) {
      $this->country = $country;
    }
  }

  /**
   * Allow users to set the converstion ratio.
   * Hopefully you are changing the percision
   * and not setting a bad value.
   *
   * @access public
   * @param  float  $rate The new value.
   * @return void
   */
  function setConversionRate($rate) {
    
    if (is_numeric($rate)) {
      $this->milesToDegrees = $rate;
    }
  }
}
/* Debugging lines
$zcr = new ZipCodesRange(10965, 10);
print_r($zcr);
*/
?>

Sets up a mysqli connection script which I retrieve with included. If a user enters the wrong password or username then the connection to the database will be interrupted, and a message will be given about this.

I want to do this in a different way. I want the .php connection script to work so that the script lets me or the ser know if it is the password that is incorrect or the username that is not authenticated. This way the user can find out if he / she has entered the wrong password or username. If both are incorrect, notice of this will be given. connection file is a fairly standard script. I have no clue about how to solve this problem. Is it posible at all? Do you know how to do it? 

 

<?
$servername = "localhost";
$username = "username";
$password = "password";

// Oppretter tilkobling.
$conn = new mysqli($servername, $username, $password);

// Kontrollerer tilkoblingen.
if ($conn->connect_error) {
  die("Tilkoblingen feilet: " . $conn->connect_error);
}
echo "Tilkoblingen var vellykket";
?>

Hello all, I'm an amateur at PHP coding, and am currently enrolled in a PHP and MySQL class that uses the PHP Programming with MySQL textbook, by Don Gosselin. I'm trying to get this simple Shopping Cart script to work, because it's the step-by-step example script for Chapter 11, but I keep getting the following errors on ShowCart.php when I try to add an item to the cart. Quote

Warning: mysqli_query() [function.mysqli-query]: Couldn't fetch mysqli in C:\xampplite\htdocs\ShoppingCart.php  on line 78

Warning: mysqli_errno() [function.mysqli-errno]: Couldn't fetch mysqli in C:\xampplite\htdocs\ShoppingCart.php on line 80

Warning: mysqli_error() [function.mysqli-error]: Couldn't fetch mysqli in C:\xampplite\htdocs\ShoppingCart.php on line 81


Line 78:        $QueryResult = mysqli_query($this->DBConnect, $SQLstring)

Line 80 and 81:             . "<p>Error code " . mysqli_errno($this->DBConnect)
            . ": " . mysqli_error($this->DBConnect)) . "</p>";

I've read "Couldn't fetch mysqli" errors are because the connection was closed prior to those lines, but I don't see any indication of a connection closure. I have no idea what to do, as all the code was given to me in the book, I merely copied it down.

Here's the ShoppingCart.php code:<?php
class ShoppingCart {
    private $DBConnect = "";
    private $DBName = "";
    private $TableName = "";
    private $Orders = array();
    private $OrderTables = array();
function construct() {
    $this->DBConnect = mysqli_connect("localhost", "root", "passHere");
    if (mysqli_connecT_errno())
        die("<p>Unable to connect to the database server.</p>"
        . "<p>Error code " . mysqli_connect_errno()
        . ": " . mysqli_connect_error()) . "</p>";
}

public function setDatabase($Database) {
    $this->DBName = $Database;
    $this->DBConnect->select_db($this->DBName)
        Or die("<p>Unable to select the databbase.</p>"
        . "<p>Error code " . mysqli_errno($this->DBConnect)
        . ": " . mysqli_error($this->DBConnect)) . "</p>";
}
public function setTable($Table) {echo $table."<br />";
    $this->TableName = $Table;
}
public function getProductList() {
    $SQLstring = "SELECT * FROM $this->TableName";
    $QueryResult = $this->DBConnect->query($SQLstring)
        Or die("<p>Error code " . mysqli_errno($this->DBConnect)
        . ": " . mysqli_error($DBConnect)) . "</p>";
    echo "<table width='100%' border='1'>";
    echo "<tr><th>Product</th><th>Description</th><th>Price Each</th><th>Select Item</th></tr>";
    $Row = $QueryResult->fetch_row();
    do {
        echo "<tr><td>{$Row[1]}</td>";
        echo "<td>{$Row[2]}</td>";
        printf("<td align='center'>$%.2f</td>", $Row[3]);
        echo "<td align ='center'>
              <a href='ShowCart.php?PHPSESSID=" . session_id()
              . "&operation=addItem&productID=" . $Row[0]
              . "'>Add</a></td></tr>";
        $Row = $QueryResult->fetch_row();
    } while ($Row);
    echo "</table>";
}
public function addItem() {
    $ProdID = $_GET['productID'];
    if (array_key_exists($ProdID, $this->Orders))
        exit("<p>You already selected that item! Click your
             browser's back button to return to the
             previous page.</p>");
    $this->Orders[$ProdID] = 1;
    $this->OrderTable[$ProdID] = $this->TableName;
}
function _wakeup() {
    $this->DBConnect = new mysqli("localhost", "staticlo_shane", "shinfoosh");
    if (mysqli_connect_errno())
        die("<p>Unable to connect to the database server.</p>"
        . "<p>Error code " . mysqli_connect_errno()
        . ": " . mysqli_connect_error()) . "</p>";
    $this->DBConnect->Select_db($this->DBName)
        Or die("<p>Unable to select the database.</p>"
        . "<p>Error code " . mysqli_errno($$this->DBConnect)
        . ": " . mysqli_error($this->DBConnect)) . "</p>";
}
public function showCart() {
    if (empty($this->Orders))
        echo "<p>Your shopping cart is empty!</p>";
    else {
        echo "<table width='100%' border='1'>";
        echo "<tr><th>Remove Item</th><th>Product</th><th>Quantity</th><th>
              Price Each</th></tr>";
        $Total = 0;
    foreach($this->Orders as $Order) {
        $SQLstring = "SELECT * FROM "
            . $this->OrderTable[key($this->Orders)] . "
            WHERE productID='" . key($this->Orders) . "'";
        $QueryResult = mysqli_query($this->DBConnect, $SQLstring)
            Or die("<p>Unable to perform the query.</p>"
            . "<p>Error code " . mysqli_errno($this->DBConnect)
            . ": " . mysqli_error($this->DBConnect)) . "</p>";
        $Row = mysqli_fetch_row($QueryResult);
        echo "<td align='center'>";
        echo "<a href='ShowCart.php?PHPSESSID=" . session_id()
              . "&operation=removeItem&productID=" . $Row[0]
              . "'>Remove</a></td>";
        echo "<td>{$Row[1]}</td>";
        echo "<td align='center''>$Order ";
echo "<a href='ShowCart.php?PHPSESSID=" . session_id() . "&operation=addOne&productID=" . $Row[0] . "'>Add</a>";
echo "<a href='ShowCart.php?PHPSESSID=" . session_id() . "&operation=removeOne&productID=" . $Row[0] . "'>Remove</a>";
        echo "</td>";
        printf("<td align='center'>$%.2f</td></tr>", $Row[3]);
        $Total += $Row[3] * $Order;
        next($this->Orders);

        echo "<td align='center' colspan='2'><strong>Your shopping
              cart contains " . count($this->Orders)
              . " product(s).</strong></td>";
        printf("<td align='center'><strong>Total: $%.2f</stong>
               </td>", $Total);
        echo "</table>";
    }
    echo "<tr><td align='center'><a href='ShowCart.php?PHPSESSID="
          . session_id() . "&operation=emptyCart'><strong>
          Empty Cart</strong></a></td>";
    }
}
public function removeItem() {
    $ProdID = $_GET['productID'];
    unset($this->Orders[$ProdID]);
    unset($this->OrderTable[$ProdID]);
}
function emptyCart() {
    $this->Orders = array();
    $this->OrderTale = array();
}
function _destruct() {
    $this->DBConnect->close();
}

public function addOne() {
$ProdID = $_GET['productID'];
$this->Orders[$ProdID] += 1;
}

public function removeOne() {
$ProdID = $_GET['productID'];
$this->Orders[$ProdID] -= 1;
if ($this->Orders[$ProdID] == 0)
$this->removeItem();
}

}
?> 

Here is the ShowCart.php code:<?php
session_start();
require_once("ShoppingCart.php");
if (!isset($_SESSION['curCart']))
header("location:GosselinGourmetGoods.php");
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<meta name="Robots" content="nofollow, noindex" />
<link rel="stylesheet" type="text/css" media="screen" href="php_styles.css" />
</head>
<body>
<h1>Gosselin Gourmet Goods</h1>
<h2>Shop by Category</h2>
<p><a href="GosselinGourmetCoffees.php">Gourmet Coffees</a><br />
<a href="GosselinGourmetOlives.php">Specialty Olives</a><br />
<a href="GosselinGourmetSpices.php">Gourmet Spices</a></p>

<?php
$Cart = unserialize($_SESSION['curCart']);
if (isset($_GET['operation'])) {
if ($_GET['operation'] == "addItem")
$Cart->addItem();
if ($_GET['operation'] == "removeItem")
$Cart->removeItem();
if ($_GET['operation'] == "emptyCart")
$Cart->emptyCart();
if ($_GET['operation'] == "addOne")
$Cart->addOne();
if ($_GET['operation'] == "removeOne")
$Cart->removeOne();
}
$Cart->showCart();
$_SESSION['curCart'] = serialize($Cart);
?>
</body>
</html>


Here is the product page for "Specialty Olives" which is identical to the Coffees and Spices pages, save for the Table name changed to their respective products: <?php
session_start();
require_once("ShoppingCart.php");
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Gosselin Gourmet Goods</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<meta name="Robots" content="nofollow, noindex" />
<link rel="stylesheet" type="text/css" media="screen" href="php_styles.css" />
</head>
<body>
<h1>Gosselin Gourmet Goods</h1>
<h2>Shop by Category</h2>
<p><a href="GosselinGourmetCoffees.php">Gourmet Coffees</a><br />
<a href="GosselinGourmetOlives.php">Specialty Olives</a><br />
<a href="GosselinGourmetSpices.php">Gourmet Spices</a></p>

<h2>Speciality Olives</h2>
<?php

$Database = "gosselin_gourmet";
$Table = "olives";

$Cart=!empty($_SESSION['curCart'])?unserialize($_SESSION['curCart']):new ShoppingCart();
$Cart->construct();
$Cart->setDatabase($Database);
$Cart->setTable($Table);
$Cart->getProductList();
$_SESSION['curCart'] = serialize($Cart);
?>
<p><a href='<?php echo "ShowCart.php?PHPSESSID=" . session_id() ?>'>Show Shopping Cart</a></p>
</body>
</html>

When running the following code i get the error:

Call to undefined method mysqli::errno() 

the code:
$conn = new mysqli(HOST, USER, PASSWORD, DATABASE);
if ($conn->errno() !== 0)
{
$msg = $conn->error();
throw new connErrorException($msg, 'Connect');
}

I am fairly new to classes but as i understand it this should be correct. I am using mysql 5.1 so mysqli is on by default. I have even checked the php ini and everything looks fine there in respect to this. Any advice?