protected function _callAggregateDbFunction($sqlFunction, $column)
        {
            $alias          = Inflector::lower($sqlFunction);
            $sqlFunction    = Inflector::upper($sqlFunction);

            if('*' != $column) {
                $column = $this->_quoteIdentifier($column);
            }

            $result_columns = $this->_resultColumns;
            $this->_resultColumns = [];
            $this->select_expr("$sqlFunction($column)", $alias);
            $result = $this->find_one();
            $this->_resultColumns = $result_columns;

            $returnValue = 0;

            if ($result !== false && isset($result->$alias)) {
                if (!is_numeric($result->$alias)) {
                    $returnValue = $result->$alias;
                }
                elseif((int) $result->$alias == (float) $result->$alias) {
                    $returnValue = (int) $result->$alias;
                } else {
                    $returnValue = (float) $result->$alias;
                }
            }

            return $returnValue;
        }