change_text_format.php

/**
 * Change content from one input format to another, deleting the old at the end.
 *
 * @param string $old_format
 *   Name of the old input format.
 * @param string $new_type
 *   Name of the new input format.
 */
function _myprofile_install_change_input_format($old_format, $new_format) {
  // Change the format on all fields.
  $fields = field_info_field_map();
  foreach ($fields as $field_name => $field_info_lite) {
    if (in_array($field_info_lite['type'], array('text_long', 'text_with_summary'))) {
      $field_info = field_info_field($field_name);
      if (empty($field_info['storage']['details']['sql'])) {
        // If there is no SQL storage information, skip it!
        continue;
      }
      foreach ($field_info['storage']['details']['sql'] as $table_info) {
        foreach ($table_info as $table_name => $column_info) {
          db_update($table_name)
            ->fields(array($column_info['format'] => $new_format))
            ->condition($column_info['format'], $old_format)
            ->execute();
        }
      }
    }
  }

  // Change the format on all blocks.
  db_update('block_custom')
    ->fields(array('format' => $new_format))
    ->condition('format', $old_format)
    ->execute();

  // Delete the format afterward.
  db_delete('filter')
    ->condition('format', $old_format)
    ->execute();
  db_delete('filter_format')
    ->condition('format', $old_format)
    ->execute();

  // Clear the cache so deletion takes in the UI.
  cache_clear_all('filter_formats:', 'cache', TRUE);
}