这是我的文件数据：

86246,205,7,707,1078778070,12564,3/2/2012,12,OZ,1,7.59
86246,63,6319,107654575,17876,64,1.59
86246,97,9753,1022027929,CT,5.99
86246,25,2509,107996777,31373,16,1.99
86246,55,5555,107684070,32094,2,10.38
12277270,95,11,1114,107027272,5613,5/25/2013,32,5.49
12277270,26,2622,102570020,20361,30,4.79
12277270,9,902,104400040,19783,8.5,1.88
12277270,27,2704,103270030,7966,13.99
12277270,10000,6.7

按照我执行的步骤获取数据：

第1步：

transaction = LOAD 'projectDemo2/part-m-00000' USING PigStorage(',') as(id:chararray,chain:chararray,dept:chararray,category:chararray,company:chararray,brand:chararray,date:chararray,productsize:float,productmeasure:chararray,purchasequantity:int,purchaseamount:float);

第2步

chainGroupCust = GROUP transactions BY (chain,id);

第3步

chainGroupCustSpedings1 = FOREACH chainGroupCust GENERATE group,SUM(transactions.purchaseamount)
as spendings;

第4步

chainGroupCustSpendings2= FOREACH chainGroupCustSpedings1 generate group.chain as chain,group.id as 
id,spendings;

第5步

chainGroupCustSpendings3= GROUP chainGroupCustSpendings2 BY chain;

第6步

chainTop10Cust = FOREACH chainGroupCustSpendings3{
chainGroupCustSpedingsSort = ORDER chainGroupCustSpendings2 BY spendings DESC;
top10Cust = LIMIT chainGroupCustSpedingsSort 10;
GENERATE top10Cust;
}

执行步骤6 时，出现以下错误：

表达式不是项目表达式：（名称：ScalarExpression）类型：null Uid：null）

有人可以帮我吗？