Drupal 7 - Useful hook_update_N

foo.php

<?php

/**
 * Uninstall modules.
 */
function foo_update_7001() {
  module_disable(array('module1', 'module2'));
  drupal_uninstall_modules(array('module1', 'module2'));
}

/**
 * Delete role.
 */
function foo_update_7002() {
  user_role_delete('role 1');
}

/**
 * Install modules.
 */
function foo_update_7003() {
  module_enable(array('module1', 'module2'));
}

/**
 * Add role visibility to a block.
 */
function foo_update_7004() {
  $module = 'module1';
  $delta = 'delta';
  $role = user_role_load_by_name('role 1');
  db_insert('block_role')
    ->fields(array('rid', 'module', 'delta'))
    ->values(array('rid' => $role->rid, 'module' => $module, 'delta' => $delta))
    ->execute();
}

/**
 * Delete tables.
 */
function foo_update_7005() {
  db_delete('table_name')
    ->execute();
}

/**
* Disable rule.
*/
function foo_update_7006() {
  if ($rules_config = rules_config_load('rules_foo_rule1')) {
    $rules_config->active = FALSE;
    $rules_config->save();
  }
}

/**
* Revert rule.
*/
function foo_update_7007() {
  if ($rules_config = rules_config_load('rules_foo_rule1')) {
    $rules_config->delete();
  }
}

/**
* Revert features.
*/
function foo_update_7008() {
  features_revert(array('lth_features' => array('features_component')));
}

/**
* Delete multiple custom blocks.
*/
function foo_update_7009() {
  $module = 'block';
  $deltas = array('24', '25');
  foreach ($deltas as $delta) {
    db_delete('block')
      ->condition('module', $module)
      ->condition('delta', $delta)
      ->execute();
    db_delete('block_custom')
      ->condition('bid', $delta)
      ->execute();
    db_delete('block_role')
      ->condition('module', $module)
      ->condition('delta', $delta)
      ->execute();
  }
}

/**
 * Add permissions.
 */
function foo_update_7010() {
  user_role_grant_permissions(DRUPAL_ANONYMOUS_RID, array('permission name')); // Anonymous users
  user_role_grant_permissions(DRUPAL_AUTHENTICATED_RID, array('permission name')); // Authentificated users
  user_role_grant_permissions(3, array('permission name')); // Role ID
}

/**
* Delete nodes and content types.
*/
function foo_update_7011() {
  $types = array(
    'forum',
    'poll',
  );
  foreach($types as $type) {
    // First, delete nodes
    $results = db_select('node', 'n')
                ->fields('n', array('nid'))
                ->condition('type', $type)
                ->execute();
    foreach ($results as $result) {
      $nids[] = $result->nid;
    }
    if (!empty($nids)) {
      node_delete_multiple($nids);
      drupal_set_message(t('%count nodes has been deleted.', array('%count' => count($nids))));
    }
    // Then, delete content type
    if (node_type_load($type)) {
      node_type_delete($type);
      variable_del('node_preview_' . $type);
      drupal_set_message(t('%type content type has been deleted.', array('%type' => $type)));
    }
  }
  node_types_rebuild();
  menu_rebuild();
}

/**
* Add OG roles.
*/
function foo_update_7011() {
  $group = 'node';
  $bundle = 'group';

  // Create new OG roles
  $roles = array(
    'Role 1',
    'Role 2',
  );
  foreach ($roles as $role) {
    $role = og_role_create($role, $group, 0, $bundle);
    og_role_save($role);
  }
}

/**
* Change OG permissions.
*/
function foo_update_7012() {
  $group = 'node';
  $bundle = 'circle';

  // Change permissions
  $og_roles = array_flip(og_roles($group, $bundle));

  // Member role
  $permissions = array(
    'permission 1' => 0,
    'permission 2' => 0,
  );
  og_role_change_permissions($og_roles[OG_AUTHENTICATED_ROLE], $permissions);

  // Custom role
  $permissions = array(
    'permission 1' => 1,
    'permission 2' => 1,
  );
  og_role_change_permissions($og_roles['Custom member'], $permissions);
}

/**
* Create new menu link.
*/
function foo_update_7013() {
  $item = array(
    'link_path' => '<front>',
    'link_title' => 'Home',
    'menu_name' => 'top-menu',
    'weight' => -50,
    'expanded' => 0,
    'module' => 'menu',
  );
  menu_link_save($item);
}

/**
* Update menu link.
*/
function foo_update_7014() {
    db_update('menu_links')
    ->fields(array(
      'link_title' => 'New link name',
      'expanded' => '1',
      'weight' => '-47',
      'hidden' => '0',
    ))
    ->condition('mlid', '7577')
    ->execute();

  menu_rebuild();
}