# processes all trades which occured between start and end date, calling $action for each one
sub processTrades {
	my ($self,$action) = @_;
	my $count = 0;
	my $trdstmt = $self->_getTradesStatement();
	$trdstmt->bind_param(1,$self->{'startdate'});
	$trdstmt->bind_param(2,$self->{'enddate'});
	$trdstmt->execute(); 
	while(my $trade = $trdstmt->fetchrow_hashref()) {
		&$action($$trdstmt->fetchrow_hashref());
		$count++;
	}
	return $count;
}