code: func (c *Chunk) AppendDatum(colIdx int, d *types.Datum) {
  	switch d.Kind() {
  	case types.KindNull:
  		c.AppendNull(colIdx)
  	case types.KindInt64:
  		c.AppendInt64(colIdx, d.GetInt64())
  	case types.KindUint64:
  		c.AppendUint64(colIdx, d.GetUint64())
  	case types.KindFloat32:
  		c.AppendFloat32(colIdx, d.GetFloat32())
  	case types.KindFloat64:
  		c.AppendFloat64(colIdx, d.GetFloat64())
  	case types.KindString, types.KindBytes, types.KindBinaryLiteral, types.KindRaw, types.KindMysqlBit:
  		c.AppendBytes(colIdx, d.GetBytes())
  	case types.KindMysqlDecimal:
  		c.AppendMyDecimal(colIdx, d.GetMysqlDecimal())
  	case types.KindMysqlDuration:
  		c.AppendDuration(colIdx, d.GetMysqlDuration())
  	case types.KindMysqlEnum:
  		c.AppendEnum(colIdx, d.GetMysqlEnum())
  	case types.KindMysqlSet:
  		c.AppendSet(colIdx, d.GetMysqlSet())
  	case types.KindMysqlTime:
  		c.AppendTime(colIdx, d.GetMysqlTime())
  	case types.KindMysqlJSON:
  		c.AppendJSON(colIdx, d.GetMysqlJSON())
  	}
  }
docs: // AppendDatum appends a datum into the chunk.