protected function getStatement($statement)
    {
        $key = $this->getStatementKey($statement);
    	$sth = null;
    	
    	if (!empty($this->statements[$key])){
    		$sth = $this->statements[$key];
    	}
    	else{
    		$sth = $this->dbConnector->prepare($statement);
    		$this->statements[$key] = $sth;
    	}
    	
    	return $sth;

    }