[SOLVED] help extending a class

[c_shelswell]

Hi still learning classes and I think there's a better way to do what i'm doing. I have a database class  which logs on to db and does any queries I need. I'm also making a form class in a separate file when a user submits a registration it checks if the username is taken for this it needs the database class. I'm calling it like this:

 

<?php
class form
{

public function checkFields($postData)
    {

    	/** check username available **/
    	$db = new db();
	$data = array('fields'=>'username', 'table'=>'registered_users', 'where'=>'username="'.$postData['username'].'"');
	$rtn = $db->selectFromDB($data);

	if ($rtn[0]->username > '')
	{
		$this->setError('username', '<br />This user name is already in use. Please choose another.');
	}
}
?>

 

but can't I have something like

<?php

class form extends db{

    public function checkFields($postData)
    {

    	/** check username available **/
    	
	$data = array('fields'=>'username', 'table'=>'registered_users', 'where'=>'username="'.$postData['username'].'"');
                $rtn = db::selectFromDB($data);
   }
}
?>

 

if i do it the 2nd way it seems to call the db class as I get a mysql access denied error so i guess it's not calling the database constructor? I don't think i'm fully grasping the extends concept I have been reading up on it but some help would be great. The start of my database class is below cheers:

<?php
class db
{
private $dbUser;
private $dbName;
private $dbPass;
private $dbServer;
private $connection;
private $result;


public function __construct($dbUser=DB_USER, $dbName=DB_NAME, $dbPass=DB_PASS, $dbServer=DB_SERVER)
{
	$this->dbUser = $dbUser;
	$this->dbName = $dbName;
	$this->dbPass = $dbPass;
	$this->dbServer = $dbServer;

	$this->connect();	
}

private function connect()
{
	$this->connection = mysql_pconnect($this->dbServer, $this->dbUser, $this->dbPass) or die (mysql_error());
 	mysql_select_db($this->dbName, $this->connection)or die(mysql_error());
}

private function disconnect()
{
	mysql_close($this->connection);
}

public function selectFromDB($data)
{
	extract($data);

	$sql = 'SELECT '.$fields.' FROM '.$table;

	if(!empty($where))
	{
		$sql .= ' WHERE '.$where;
	}

	if(!empty($groupBy))
	{
		$sql .= ' GROUP BY '.$groupBy;
	}

	if(!empty($orderBy))
	{
		$sql .= ' ORDER BY '.$orderBy;
	}

	if(!empty($limit))
	{
		$sql .= ' LIMIT '.$limit;
	}

	$this->result = $this->query($sql);


	if($this->result)
	{
		$rows = $this->fetchRows();
	}

	return $rows;
}
}
?>

 

 

 

[Mark Baker]

In your form class constructor, you need to have a call to parent::_construct()

[c_shelswell]

Great thanks very much - works a treat!