APACHE PIG - 模式中不存在错误投影字段 [Units_Sold]：group:chararray,D2:bag{:tuple(Item_Type:chararray,Units_Sold:int)}

Question

下午好 - 我有一个销售数据集，我正在尝试查看哪个商品的销量最多。 这是我的代码：

        Country:chararray,
        Item_Type:chararray,
        Sales_Channel:chararray,
        Order_Priority_site:chararray,
        Order_Date:chararray,
        Order_ID:chararray,
        Ship_Date:chararray,
        Units_Sold:int,
        Unit_Price: int,
        Unit_Cost: int,
        Total_Revenue: int,
        Total_Cost: int,
        Total_Profit:int);

D2 = FOREACH data GENERATE Item_Type, Units_Sold;

D3 = GROUP D2 BY Item_Type;

D4 = FOREACH D3 GENERATE group, SUM(Units_Sold);

DUMP D4;```

However, I get the error: 

```<file D, line 20, column 36> Invalid field projection. Projected field [Units_Sold] does not exist in schema: group:chararray,D2:bag{:tuple(Item_Type:chararray,Units_Sold:int)}.```

Does anybody know how to fix this? Let me know if you need more info, this is the first qurstion I have posted on here

Answer 1

SUM 正在等待一个袋子。错误显示了架构：

D2:bag{:tuple(Item_Type:chararray,Units_Sold:int)}

因此将 SUM 更改为：

SUM(D2.Units_Sold)