InsertQuery::addOneValue PHP Method

    private function addOneValue($oneValue)
    {
        // check if all $keys are strings
        foreach ($oneValue as $key => $value) {
            if (!is_string($key)) {
                throw new Exception('INSERT query: All keys of value array have to be strings.');
            }
        }
        if (!$this->firstValue) {
            $this->firstValue = $oneValue;
        }
        if (!$this->columns) {
            $this->columns = array_keys($oneValue);
        }
        if ($this->columns != array_keys($oneValue)) {
            throw new Exception('INSERT query: All VALUES have to same keys (columns).');
        }
        $this->statements['VALUES'][] = $oneValue;
    }