code: func compareTime(a, b MysqlTime) int {
  	ta := datetimeToUint64(a)
  	tb := datetimeToUint64(b)
  
  	switch {
  	case ta < tb:
  		return -1
  	case ta > tb:
  		return 1
  	}
  
  	switch {
  	case a.Microsecond() < b.Microsecond():
  		return -1
  	case a.Microsecond() > b.Microsecond():
  		return 1
  	}
  
  	return 0
  }
docs: // compareTime compare two MysqlTime.
  // return:
  //  0: if a == b
  //  1: if a > b
  // -1: if a < b