private function upgradeTblQuote($setup)
    {
        $conn = $setup->getConnection();
        $table = $setup->getTable(EPartQuote::ENTITY_NAME);

        /* add columns */
        $conn->addColumn(
            $table,
            EPartQuote::A_BASE_CURRENCY,
            [
                'type' => \Magento\Framework\DB\Ddl\Table::TYPE_TEXT,
                'length' => 3,
                'nullable' => false,
                'after' => EPartQuote::A_BASE_PARTIAL_AMOUNT,
                'comment' => 'Currency code for base amount (stock/warehouse currency).'
            ]
        );
        $conn->addColumn(
            $table,
            EPartQuote::A_CURRENCY,
            [
                'type' => \Magento\Framework\DB\Ddl\Table::TYPE_TEXT,
                'length' => 3,
                'nullable' => false,
                'after' => EPartQuote::A_PARTIAL_AMOUNT,
                'comment' => 'Currency code for amount (payment??? currency).'
            ]
        );
    }