gistfile1.php

<?php

/**
 * Implementation of hook_drush_command().
 */
function updaterollback_drush_command() {
  $items['update-get-schema'] = array(
    'description' => 'Drop all tables in a given database.',
    'arguments' => array(
      'module' => 'module',
    ),
    'bootstrap' => DRUSH_BOOTSTRAP_MAX,
  );
  $items['update-rollback'] = array(
    'description' => '',
    'arguments' => array(
      'module' => 'module',
      'schema' => 'schema',
    ),
    'bootstrap' => DRUSH_BOOTSTRAP_MAX,
  );
  return $items;
}

function drush_updaterollback_update_rollback($module, $schema = NULL) {
  require_once './includes/install.inc';
  drupal_load_updates();

  $current_schema = drupal_get_installed_schema_version($module);
  $schema = $current_schema - 1;
  if ($schema) {
    drupal_set_installed_schema_version($module, $schema - 1);
    drush_log(dt("!module's schema rolled back to !schema!", array('!module' => $module, '!schema' => $schema)));
  }
  else {
    drush_set_error(dt("!schema is not a valid schema for !module!", array('!schema' => $schema, '!module' => $module)));
  }
}

function drush_updaterollback_update_get_schema() {
  require_once './includes/install.inc';
  $modules = func_get_args();
  drupal_load_updates();
  $schemas = array();
  foreach ($modules as $module) {
    $schemas[$module] = drupal_get_installed_schema_version($module);
  }
  drush_print_table(drush_key_value_to_array_table($schemas));
}