framework/db/conditions/BetweenColumnsConditionBuilder.php
protected function escapeColumnName($columnName, &$params = [])
    {
        if ($columnName instanceof Query) {
            list($sql, $params) = $this->queryBuilder->build($columnName, $params);
            return "($sql)";
        } elseif ($columnName instanceof ExpressionInterface) {
            return $this->queryBuilder->buildExpression($columnName, $params);
        } elseif (strpos($columnName, '(') === false) {
            return $this->queryBuilder->db->quoteColumnName($columnName);
        }

        return $columnName;
    }
protected function escapeColumnName($columnName, &$params = [])
    {
        if ($columnName instanceof Query) {
            list($sql, $params) = $this->queryBuilder->build($columnName, $params);
            return "($sql)";
        } elseif ($columnName instanceof ExpressionInterface) {
            return $this->queryBuilder->buildExpression($columnName, $params);
        } elseif (strpos($columnName, '(') === false) {
            return $this->queryBuilder->db->quoteColumnName($columnName);
        }

        return $columnName;
    }
Prepares column name to be used in SQL statement.

@param Query|ExpressionInterface|string $columnName
@param array $params the binding parameters.
@return string