//Below is the write function from a session handler class i created for a custom site:
//This allows tracking of logged in users, logging recently viewed pages and who's online/offline

    function write ($session_id, $session_data)
    {
        $ret = @$this->sql->query ("SELECT * FROM `{$this->table}` WHERE `SESSION_ID` = '$session_id' LIMIT 1", true, $this->db);
        $expire = $this->now + $this->sessionLifetime;
        $arr_data = array (
            'SESSION_DATA'        => $session_data,
            'SESSION_EXPIRE'    => $expire,
        );
        global $track;
        if ($ret)
        {
            @$this->sql->arr_update ($this->table, $arr_data, 'SESSION_ID', $session_id, $this->db);
            if (@$this->sql->affected_rows ())
            {
                if ($ret['LOGIN_ID']) @$track->last_seen ($ret['LOGIN_ID'], $ret['LOGIN_TYPE']);
                return true;
            }
        } else {
            $arr_data['SESSION_ID'] = $session_id;
            $arr_data['LOGIN_TYPE'] = $_SESSION['LOGIN']['TYPE'];
            $arr_data['LOGIN_ID'] = $_SESSION['LOGIN']['ID'];
            @$this->sql->arr_insert ($this->table, $arr_data, $this->db);
            if (@$this->sql->affected_rows ())
            {
                if ($_SESSION['LOGIN']['ID']) @$track->last_seen ($_SESSION['LOGIN']['ID'], $_SESSION['LOGIN']['TYPE']);
                return true;
            }
        }
        return false;
    }

//Below is a simple array inserting function for MySQL:
//This will take the array of fields and values, and place it into a query sent to the database server

    function arr_insert($tbl, $arr, $db='', $escape=false)
    {
        $str_q_left = "INSERT INTO $tbl (";
        $str_q_mid = ') VALUES (';
        $str_q_right = ')';
        end($arr);
        $last_key=key($arr);
        foreach ($arr as $key => $elem) {
            $str_q_left .= "`$key`";
            $str_q_mid .= ($escape || (substr($elem, 0, 1)!='\'' && substr($elem, -1)!='\'')) ? "'$elem'" : $elem;
            if ($key!=$last_key){
                $str_q_left .=  ', ';
                $str_q_mid .= ', ';
            }
        }
        $str_q = $str_q_left . $str_q_mid . $str_q_right;
        return $this->query($str_q, false, $db);
    }