.install

<?php

/**
 * @file
 * Install, update and uninstall functions for the hello module.
 */

use Drupal\Core\Database\Database;

/**
 * Implements hook_schema().
 */
function hello_schema() {
  $schema['hello_node_history'] = array(
    'description' => 'Stores node update history.',
    'fields' => array(
      'hid' => array(
        'type'        => 'serial',
        'unsigned'    => TRUE,
        'not null'    => TRUE,
      ),
      'nid' => array(
        'type'        => 'int',
        'unsigned'    => TRUE,
        'not null'    => TRUE,
      ),
      'uid' => array(
        'type'        => 'int',
        'unsigned'    => TRUE,
        'not null'    => TRUE,
      ),
      'update_time' => array(
        'type'        => 'int',
        'unsigned'    => TRUE,
        'not null'    => TRUE,
      ),
    ),
    'primary key' => array('hid'),
    'indexes' => array('nid' => array('nid')),
  );
  return $schema;
}

/**
 * Implements hook_update_N().
 */
/**
 * Add a 'uid' field to the hello_node_history table.
 */
function hello_update_8300() {
  $field_spec = array(
    'type'        => 'int',
    'description' => "Store user ID.",
    'unsigned'    => TRUE,
    'not null'    => TRUE,
  );
  $schema = Database::getConnection()->schema();
  $schema->addField('hello_node_history', 'uid', $field_spec);
}