text: ALTER TABLE period_type
  MODIFY COLUMN fromtime bigint(8) NOT NULL;
  
  ALTER TABLE period_type
  MODIFY COLUMN totime bigint(8) NOT NULL;
  
  
  ALTER TABLE periods
  MODIFY COLUMN periodfrom bigint(8) NOT NULL;
  
  ALTER TABLE periods
  MODIFY COLUMN periodto bigint(8) NOT NULL;
  
  