InstallSchema.php

<?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */

namespace Magento\OfflineShipping\Setup;

use Magento\Framework\Setup\InstallSchemaInterface;
use Magento\Framework\Setup\ModuleContextInterface;
use Magento\Framework\Setup\SchemaSetupInterface;

/**
 * @codeCoverageIgnore
 */
class InstallSchema implements InstallSchemaInterface
{
    /**
     * @var string
     */
    private static $quoteConnectionName = 'checkout';

    /**
     * @var string
     */
    private static $salesConnectionName = 'sales';

    /**
     * {@inheritdoc}
     * @SuppressWarnings(PHPMD.ExcessiveMethodLength)
     */
    public function install(SchemaSetupInterface $setup, ModuleContextInterface $context)
    {
        $installer = $setup;

        $installer->startSetup();

        /**
         * Create table 'shipping_tablerate'
         */
        $table = $installer->getConnection()->newTable(
            $installer->getTable('shipping_tablerate')
        )->addColumn(
            'pk',
            \Magento\Framework\DB\Ddl\Table::TYPE_INTEGER,
            null,
            ['identity' => true, 'unsigned' => true, 'nullable' => false, 'primary' => true],
            'Primary key'
        )->addColumn(
            'website_id',
            \Magento\Framework\DB\Ddl\Table::TYPE_INTEGER,
            null,
            ['nullable' => false, 'default' => '0'],
            'Website Id'
        )->addColumn(
            'dest_country_id',
            \Magento\Framework\DB\Ddl\Table::TYPE_TEXT,
            4,
            ['nullable' => false, 'default' => '0'],
            'Destination coutry ISO/2 or ISO/3 code'
        )->addColumn(
            'dest_region_id',
            \Magento\Framework\DB\Ddl\Table::TYPE_INTEGER,
            null,
            ['nullable' => false, 'default' => '0'],
            'Destination Region Id'
        )->addColumn(
            'dest_zip',
            \Magento\Framework\DB\Ddl\Table::TYPE_TEXT,
            10,
            ['nullable' => false, 'default' => '*'],
            'Destination Post Code (Zip)'
        )->addColumn(
            'condition_name',
            \Magento\Framework\DB\Ddl\Table::TYPE_TEXT,
            20,
            ['nullable' => false],
            'Rate Condition name'
        )->addColumn(
            'condition_value',
            \Magento\Framework\DB\Ddl\Table::TYPE_DECIMAL,
            '12,4',
            ['nullable' => false, 'default' => '0.0000'],
            'Rate condition value'
        )->addColumn(
            'price',
            \Magento\Framework\DB\Ddl\Table::TYPE_DECIMAL,
            '12,4',
            ['nullable' => false, 'default' => '0.0000'],
            'Price'
        )->addColumn(
            'cost',
            \Magento\Framework\DB\Ddl\Table::TYPE_DECIMAL,
            '12,4',
            ['nullable' => false, 'default' => '0.0000'],
            'Cost'
        )->addIndex(
            $installer->getIdxName(
                'shipping_tablerate',
                ['website_id', 'dest_country_id', 'dest_region_id', 'dest_zip', 'condition_name', 'condition_value'],
                \Magento\Framework\DB\Adapter\AdapterInterface::INDEX_TYPE_UNIQUE
            ),
            ['website_id', 'dest_country_id', 'dest_region_id', 'dest_zip', 'condition_name', 'condition_value'],
            ['type' => \Magento\Framework\DB\Adapter\AdapterInterface::INDEX_TYPE_UNIQUE]
        )->setComment(
            'Shipping Tablerate'
        );
        $installer->getConnection()->createTable($table);

        $installer->getConnection()->addColumn(
            $installer->getTable('salesrule'),
            'simple_free_shipping',
            \Magento\Framework\DB\Ddl\Table::TYPE_SMALLINT,
            null,
            ['unsigned' => true, 'nullable' => false, 'default' => '0'],
            'Simple Free Shipping'
        );
        $installer->getConnection(self::$salesConnectionName)->addColumn(
            $installer->getTable('sales_order_item', self::$salesConnectionName),
            'free_shipping',
            \Magento\Framework\DB\Ddl\Table::TYPE_SMALLINT,
            null,
            ['unsigned' => true, 'nullable' => false, 'default' => '0'],
            'Free Shipping'
        );
        $installer->getConnection(self::$quoteConnectionName)->addColumn(
            $installer->getTable('quote_address', self::$quoteConnectionName),
            'free_shipping',
            \Magento\Framework\DB\Ddl\Table::TYPE_SMALLINT,
            null,
            ['unsigned' => true, 'nullable' => false, 'default' => '0'],
            'Free Shipping'
        );
        $installer->getConnection(self::$quoteConnectionName)->addColumn(
            $installer->getTable('quote_item', self::$quoteConnectionName),
            'free_shipping',
            \Magento\Framework\DB\Ddl\Table::TYPE_SMALLINT,
            null,
            ['unsigned' => true, 'nullable' => false, 'default' => '0'],
            'Free Shipping'
        );
        $installer->getConnection(self::$quoteConnectionName)->addColumn(
            $installer->getTable('quote_address_item', self::$quoteConnectionName),
            'free_shipping',
            \Magento\Framework\DB\Ddl\Table::TYPE_INTEGER,
            null,
            ['unsigned' => true],
            'Free Shipping'
        );

        $installer->endSetup();

    }
}