Apache pig 通过在PIG脚本中的不同块内计算的条件值在FOREACH块内进行过滤

我有2个数据集，我需要找到匹配记录的匹配记录 从数据集1到数据集2，如下所示：

dataset 1 = [sourceID, details, key]
1, details1, 1111
2, details2, 1112
3, details3, 1113
4, details4, 1114
...

dataset2 = [key1, key2, number]
1111,1112,3
1111,1114,1
1112,1113,11
 ...

output: 
1, details1, 1111, 2, details2, 1112, 3
1, details1,1111, 4, details4, 1114, 1
2, details2, 1112, 3, details3, 11
....

我做了如下尝试：

a = foreach dataset1 {
        b = filter dataset2 by dataset1.key1 matches dataset1.key;
        c = filter dataset2 by datset1.key2 matches dataset1.key; 
        generate b, c;
    };

请帮忙

非常感谢。

运行两个连接

B = join dataset1 by key, dataset2 by key1;
C = join dataset1 by key, B by key2;

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谢谢你的回答。