code: func IntergerSignedUpperBound(intType byte) int64 {
  	switch intType {
  	case mysql.TypeTiny:
  		return math.MaxInt8
  	case mysql.TypeShort:
  		return math.MaxInt16
  	case mysql.TypeInt24:
  		return mysql.MaxInt24
  	case mysql.TypeLong:
  		return math.MaxInt32
  	case mysql.TypeLonglong:
  		return math.MaxInt64
  	default:
  		panic("Input byte is not a mysql type")
  	}
  }
docs: // IntergerSignedUpperBound indicates the max int64 values of different mysql types.