code: func (bf *bitAndFunction) Update(evalCtx *AggEvaluateContext, sc *stmtctx.StatementContext, row chunk.Row) error {
  	a := bf.Args[0]
  	value, err := a.Eval(row)
  	if err != nil {
  		return err
  	}
  	if !value.IsNull() {
  		if value.Kind() == types.KindUint64 {
  			evalCtx.Value.SetUint64(evalCtx.Value.GetUint64() & value.GetUint64())
  		} else {
  			int64Value, err := value.ToInt64(sc)
  			if err != nil {
  				return err
  			}
  			evalCtx.Value.SetUint64(evalCtx.Value.GetUint64() & uint64(int64Value))
  		}
  	}
  	return nil
  }
docs: // Update implements Aggregation interface.