text: SET @preparedStatement = (SELECT IF(
      (
          SELECT COUNT(*) FROM INFORMATION_SCHEMA.STATISTICS
          WHERE table_name = 'UserGroups'
          AND table_schema = DATABASE()
          AND index_name = 'idx_usergroups_displayname'
      ) > 0,
      'DROP INDEX idx_usergroups_displayname ON UserGroups;',
      'SELECT 1'
  ));
  
  PREPARE removeIndexIfExists FROM @preparedStatement;
  EXECUTE removeIndexIfExists;
  DEALLOCATE PREPARE removeIndexIfExists;