We then set up a second selector that specifies a sequence number of 2 along with the group identifier.

然后，我们将设置第二个选择器，以执行序列号2和相应的组标识符。

youdao

This differs from the result selector in a non-group join, which cannot access elements from the first collection that have no match in the second collection.

这与无群组联结的结果选取器不同，如果在第二个集合中没有相符项目，该选取器就无法存取第一个集合中的项目。

youdao