InstallSchema.php

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

namespace Magento\AdminNotification\Setup;

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

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

        $installer->startSetup();
        /**
         * Create table 'adminnotification_inbox'
         */
        $table = $installer->getConnection()->newTable(
            $installer->getTable('adminnotification_inbox')
        )->addColumn(
            'notification_id',
            \Magento\Framework\DB\Ddl\Table::TYPE_INTEGER,
            null,
            ['identity' => true, 'unsigned' => true, 'nullable' => false, 'primary' => true],
            'Notification id'
        )->addColumn(
            'severity',
            \Magento\Framework\DB\Ddl\Table::TYPE_SMALLINT,
            null,
            ['unsigned' => true, 'nullable' => false, 'default' => '0'],
            'Problem type'
        )->addColumn(
            'date_added',
            \Magento\Framework\DB\Ddl\Table::TYPE_TIMESTAMP,
            null,
            ['nullable' => false, 'default' => \Magento\Framework\DB\Ddl\Table::TIMESTAMP_INIT],
            'Create date'
        )->addColumn(
            'title',
            \Magento\Framework\DB\Ddl\Table::TYPE_TEXT,
            255,
            ['nullable' => false],
            'Title'
        )->addColumn(
            'description',
            \Magento\Framework\DB\Ddl\Table::TYPE_TEXT,
            '64k',
            [],
            'Description'
        )->addColumn(
            'url',
            \Magento\Framework\DB\Ddl\Table::TYPE_TEXT,
            255,
            [],
            'Url'
        )->addColumn(
            'is_read',
            \Magento\Framework\DB\Ddl\Table::TYPE_SMALLINT,
            null,
            ['unsigned' => true, 'nullable' => false, 'default' => '0'],
            'Flag if notification read'
        )->addColumn(
            'is_remove',
            \Magento\Framework\DB\Ddl\Table::TYPE_SMALLINT,
            null,
            ['unsigned' => true, 'nullable' => false, 'default' => '0'],
            'Flag if notification might be removed'
        )->addIndex(
            $installer->getIdxName('adminnotification_inbox', ['severity']),
            ['severity']
        )->addIndex(
            $installer->getIdxName('adminnotification_inbox', ['is_read']),
            ['is_read']
        )->addIndex(
            $installer->getIdxName('adminnotification_inbox', ['is_remove']),
            ['is_remove']
        )->setComment(
            'Adminnotification Inbox'
        );
        $installer->getConnection()->createTable($table);

        /**
         * Create table 'admin_system_messages'
         */
        $table = $installer->getConnection()->newTable(
            $installer->getTable('admin_system_messages')
        )->addColumn(
            'identity',
            \Magento\Framework\DB\Ddl\Table::TYPE_TEXT,
            100,
            ['nullable' => false, 'primary' => true],
            'Message id'
        )->addColumn(
            'severity',
            \Magento\Framework\DB\Ddl\Table::TYPE_SMALLINT,
            null,
            ['unsigned' => true, 'nullable' => false, 'default' => '0'],
            'Problem type'
        )->addColumn(
            'created_at',
            \Magento\Framework\DB\Ddl\Table::TYPE_TIMESTAMP,
            null,
            ['nullable' => false, 'default' => \Magento\Framework\DB\Ddl\Table::TIMESTAMP_INIT],
            'Create date'
        )->setComment(
            'Admin System Messages'
        );
        $installer->getConnection()->createTable($table);

        $installer->endSetup();

    }
}