classes and mysql connections

[littlened]

Usually when I use PHP I create an include file which contains the relevant username,password,host for the mysql connection, and I simply include this file each time I need to make a connection to the database.

I'm trying to use classes to get data from a database and return the results, however I'm not sure how I go about assigning the username,password without having to do it manually inside each class. I've tried including an external file using include() but I get an error.

Does anyone have any ideas?

[wildteen88]

Just include the file that has your database details in your
constructor or function that creates the connection to the database

Here is a simple database class:

[code]class DB {

    var $host = '';
    var $user = '';
    var $pass = '';
    var $dbase = '';

    // this gets called when we initiate the class
    // this is called a constructor
    // constructors have the same name as the class
    function DB()
    {
        // change this to location of you php file with you details
        include 'path/to/your/dbdetails.php';

        // setting up the class variables
        $this->host = $host;
        $this->user = $user;
        $this->pass = $pass;
        $this->dbase = $dbase;

        // connect to the database automatically
        $this->connect();
    }

    function connect()
    {
        $this->conn = mysql_connect($this->host, $this->user, $this->pass);

        mysql_select_db($this->dbase, $this->conn);
    }
}[/code]

When you go to connect to the database initiate the class:
[code]// connect to database.
$db = new DB;[/code]

[littlened]

thats seems fair enough, but how do I then get a function within another class to use that specific database connection?

So far I've only opened a database connection from within the same class I need to use it, so I can use $this->conn, but how do I do it from inside another class?

[trq]

You'll need to include your DB class in any other classes that need it. eg;

[code]
<?php
  class foo {
    private $db;
    function __construct() {
      include 'classes/db.class.php';
      $this->db = new DB();
    }
  }
?>[/code]

[littlened]

ok I've gave this a go but all I get is

mysql_query(): supplied argument is not a valid MySQL-Link resource in

here is the db class

[code]
class DB {

    var $host = 'localhost';
    var $user = 'dsfsdf';
    var $pass = 'dsfsdf';
    var $dbase = 'sdfsdfsdf';

    function DB()
    {
        $this->connect();
    }

    function connect()
    {
        $this->conn = mysql_connect($this->host, $this->user, $this->pass);
        mysql_select_db($this->dbase, $this->conn);
    }
}
[/code]

here is the class which calls the db class

[code]
class categories {

function categories() {

} // end categories function

function get_categories() {
include 'classes/cls_db.php';
      $this->dblink = new DB();

$categories = array();
$query = "SELECT Category_ID,Category_Name,Category_Display FROM Categories ORDER BY Category_Name ASC ";
      $result = mysql_query($query, $this->dblink);
$num_rows = mysql_num_rows($result);
while ($row = mysql_fetch_array($result)) {
$categories[] = $row;
}

return $categories;
} // end get_cats function

} // END CLASS
[/code]

and finally here is the code which calls the categories class.

[code]require_once('classes/cls_categories.php');

$categories = new categories;

$Action = $_REQUEST['a'];
if ($Action == '') $Action = 'list';

if ($Action == 'list') {
$categories_list = $categories->get_categories();
print_r($categories_list);
} // end action IF[/code]

[wildteen88]

Here:
[code]include 'classes/cls_db.php';
      $this->dblink = new DB();[/code]
is wrong. The DB Class does not return a MySQL resource link, however it does hold the resource link in a variable called conn within the DB class. What you'll want to do use this when connecting to the database:
[code]nclude 'classes/cls_db.php';
      $db = new DB();[/code]
Then to get the resource link use $db->conn intead of $this->dblink

[littlened]

ok so I've modified the code to this, but now I get the following errors:

Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/alive/public_html/clients/zund/www/manager/classes/cls_categories.php on line 16

Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in /home/alive/public_html/clients/zund/www/manager/classes/cls_categories.php on line 17

[code]
class categories {

function categories() {

} // end categories function

function get_categories() {
include 'classes/cls_db.php';
      $db = new DB();

$categories = array();
$query = "SELECT Category_ID,Category_Name,Category_Display FROM Categories ORDER BY Category_Name ASC ";
                   $result = mysql_query($query, $db->conn);
$num_rows = mysql_num_rows($result);
while ($row = mysql_fetch_array($result)) {
$categories[] = $row;
}

return $categories;
} // end get_cats function

} // END CLASS
[/code]

[wildteen88]

If you are getting that error then it more like to be an error with your query. Change this line:
[code]$result = mysql_query($query, $db->conn); [/code]
to:
[code]$result = mysql_query($query, $db->conn) or die("Error with query:<br /><pre>{$query}</pre><br /><br >" . mysql_error());[/code]
Post the error message you get in full here.

[b]EDIT:[/b]

Oh poop! I Forgot to set up the conn variable in the db class, Add the following code:
[code]var $conn = '';[/code]
after [tt]var $dbase = '';[/tt] in the DB class.

[littlened]

yes you were right, problem with my query, thanks