Re: call to a member function select() on a non object.

you already had the answer to this problem. do try to read the error message properly. a 'non object' is quite clear - if in doubt about what something is or something should be use var_dump() or print_r() to output the variable in question (e.g. $DB, which you would have seen was NULL). now for some tips ... nihilism machine schreef:

I amn trying to use my db class in my auth class, but i get the error: call to a member function select() on a non object <?php class db {

    //    Members
    private $db_user = "mydbuser";
    private $db_pass = "mypassword";
    private $db_name = "mydb";
    private $db_server = "myhost.com";

don't store these in the class - it makes the class usable only for 1 explicit project/DB, and classes are supposed to be reusable. instead pass in these connection parameters to the constructor (or something similar)

    private $link;
    private $result_id;

    //    Methods
    public function __construct() {
        $this->connect();
    }

    // Connect to MySQL Server
    private function connect() {
        $this->link = mysql_connect($this->db_server,$this->db_user,$this->db_pass) or die("ERROR - Cannot Connect to DataBase");
        mysql_select_db($this->db_name,$this->link) or die("ERROR: Cannot Select Database (" . $this->db_name .  ")");   

the 'or die("bla bla");' type of error handling is rubbish, you can use it for simple/throw-away scripts but when your writing a class you should make the error handling much more flexible and leave it up to the code that uses the class to decide how to handle the error. with the die() statement the consumer of the class has no choice about what to do if a connection error occurs.

    }

    // Disconnect from MySQL Server
    private function disconnect() {
        mysql_close($this->link);
    }
        // MySQL Select
    public function select($sql) {
        $this->result_id = $this->query($sql);
        if($this->result_id){
            $rows = $this->fetch_rows();
        }
        return $rows;

your returning $rows even if it was not created, this gives you an E_NOTICE error when you don't get a result id back.

    }

    // Insert into MySQL
    public function insert($params) {
        extract($params);

I wouldn't use extract, also your not doing any input parameter checking here.

        $sql = 'INSERT INTO '.$table.' ('.$fields.') VALUES ('.$values.')';

the preceding line has SQL injection potential written all over it.

        $this->query($sql);
        if($this->result_id){
            $affected_rows = $this->affected_rows();
        }
        return $affected_rows;       }
        // Delete from MySQL
    public function delete($params) {
        extract($params);
        $sql = 'DELETE FROM '.$table.' WHERE '.$where;
        if (is_numeric($limit)) {
            $sql .= ' LIMIT '.$limit;
        }
        $this->query($sql);
        if($this->result_id){
            $affected_rows = $this->affected_rows();
        }
        return $affected_rows;           }
        // Update MySQL
    public function update($params) {
        extract($params);
        $sql = 'UPDATE '.$table.' SET '.$values.' WHERE '.$where;
        if(is_numeric($limit)){
            $sql .= ' LIMIT '.$limit;
        }
        $this->query($sql);
        if($this->result_id){
            $affected_rows = $this->affected_rows();
        }
        return $affected_rows;
    }
        // MySQL Query
    private function query($sql) {
        $this->result_id = mysql_query($sql);
        return $this->fetch_rows();
    }               // MySQL Fetch Rows
    private function fetch_rows() {
        $rows = array();
        if($this->result_id){
            while($row = mysql_fetch_object($this->result_id)){
                $rows[] = $row;
            }                   }
        return $rows;       }
        // MySQL Affected Rows
    private function affected_rows() {
        return mysql_affected_rows($this->link);
    }

    // MySQL Affected Rows
    private function num_rows() {
        return mysql_num_rows($this->link);
    }
        // MySQL Affected Rows
    private function select_id() {
        return mysql_insert_id($this->link);
    }
        // Destruct!
    public function __destruct() {
        $this->disconnect();
    }

} ?> <?php require_once("db.class.php"); class auth {

    public $DB;
    public $UserID;
    public $AdminLevel;
    public $FirstName;
    public $LastName;
    public $DateAdded;
    public $MobileTelephone;
    public $LandLineTelephone;

public members suck.

    // Connect to the database
    public function __construct() {
        $DB = new db();

how many objects will be using a DB connection? will each one be using a new copy? consider passing in a DB object, that way your saving having to create one each time.

    }

    // Attempt to login a user
    public function CheckValidUser($Email, $Password) {
        $PasswordEncoded = $this->encode($Password);
        $rows = $DB->select("SELECT * Users WHERE Email='$Email', AND Password='$PasswordEncoded'");

again SQL injection potential, at the very least you should be using mysql_real_escape_string();

        if ($DB->num_rows > 0) {
            $this->UserID = $row['ID'];
            $this->AdminLevel = $row['Admin_Level'];
            $this->FirstName = $row['First_Name'];
            $this->LastName = $row['Last_Name'];
            $this->DateAdded = $row['Date_Added'];
            $this->MobileTelephone = $row['Telephone_Mobile'];
            $this->LandLineTelephone = $row['Telephone_Land_Line'];
            // User info stored in Sessions
            session_start();
            $_SESSION['Status'] = "loggedIn";
            $_SESSION['ID'] = $row['ID'];
            $_SESSION['Email'] = $row['Email'];
            $_SESSION['AdminLevel'] = $row['Admin_Level'];
            $_SESSION['LandLine'] = $row['Telephone_Land_Line'];
            $_SESSION['MobileTelephone'] = $row['Telephone_Mobile'];
            $_SESSION['FirstName'] = $row['First_Name'];
            $_SESSION['LastName'] = $row['Last_Name'];

here your only storing the values in the Auth object during the request that the check for a valid user is done. subsequent requests will have no values for Auth->UserID (et al). which begs the question: why bother to have these member properties at all?

        } else {
            return false;
        }
    }
        public function encode($str) {
        return md5(base64_encode($str));
    }

} ?> <?php $myauth = new auth(); $x = $myauth->CheckValidUser("test@test.com", "password"); echo $x; ?>