How to rename a cck field machine's name in Drupal 7.x

CCK Machine Name Change

$fields = array(
    'field_my_fields'      => 'field_my_new_field',
    'field_other_field'    => 'field_adam_west',
  );

  // Loop through each of the fields/tables with the old name and change them
  foreach($fields as $field_name => $new_field_name) {

    // First check that field_name exists
    if(!db_table_exists('field_data_' . $field_name)) {
      // If we cannot find a data table then just continue.
      continue;
    }

    // Define some things...
    $data_table_name = 'field_data_' . $field_name;
    $revision_table_name = 'field_revision_' . $field_name;
    $field_info = field_info_field($field_name);
    $storage_details = $field_info['storage']['details'];

    // The storage for each field has unique configuration. Must follow.
    foreach($storage_details['sql']['FIELD_LOAD_CURRENT'] as $field) {
      // Change the field names.
      foreach($field as $key => $value) {

        // Rename the field table columns and preserve existing spec. Let
        // features take care of any configuration changes.
        $spec = $field_info['columns'][$key];
        db_change_field($data_table_name, $value, $new_field_name . "_" . $key, $spec);
        db_change_field($revision_table_name, $value, $new_field_name . "_" . $key, $spec);

      }
    }

    // Change the field storage table names.
    db_rename_table($data_table_name, 'field_data_' . $new_field_name);
    db_rename_table($revision_table_name, 'field_revision_' . $new_field_name);

    // Change the field names int he field_config and
    // field_instance_config tables

    db_update('field_config')
      ->fields(
        array(
          'field_name' => $new_field_name,
        )
      )
      ->condition('field_name', $field_name, '=')
      ->execute();

    db_update('field_config_instance')
      ->fields(
        array(
          'field_name' => $new_field_name,
        )
      )
      ->condition('field_name', $field_name, '=')
      ->execute();

  } /// end foreach loop on fields... whew.