Can't get Insert to work from one class to another

[PaulMilo]

Hi
I have a DB class which makes a connection and provides a method to send in queries as follows:
function query($sql)
{
$this->result = @mysql_query($s ql, $this->conn);
return($this->result != false);
}
I have an INSERT class that does this:
class INSERT
{
var $username = '';
var $password = '';
var $tablename = '';

function insert($usernam e,$password,$ta blename)
{
$insertquery = "insert into" . $tablename . "(secLoginID,se cPassword) values (" . $username . "," . $password . ")";
function doInsert (){return $this->insertquery; }
}
}
and I have a test page that does this:
if ($db){
$myinsert = new INSERT(paul,mik e,security);
$db->query('$myinse rt->doInsert');
$myaffected = $db->affectedRows() ;
echo("number of affected rows is " . $myaffected . "<br><br>") ;
} ELSE {
die($db->error());
}
the affected rows function already works and is telling me that the insert is not happening.

can anyone see what's wrong ?

thx,

Paul