code: func (ts *TiDBStatement) AppendParam(paramID int, data []byte) error {
  	if paramID >= len(ts.boundParams) {
  		return mysql.NewErr(mysql.ErrWrongArguments, "stmt_send_longdata")
  	}
  	// If len(data) is 0, append an empty byte slice to the end to distinguish no data and no parameter.
  	if len(data) == 0 {
  		ts.boundParams[paramID] = []byte{}
  	} else {
  		ts.boundParams[paramID] = append(ts.boundParams[paramID], data...)
  	}
  	return nil
  }
docs: // AppendParam implements PreparedStatement AppendParam method.