Question

我在linq中找到了这个嵌套组的例子。如果我想再添加一个group by，它会怎样？

  var queryNestedGroups =
        from student in students
        group student by student.Year into newGroup1
        from newGroup2 in
            (from student in newGroup1
             group student by student.LastName)
        group newGroup2 by newGroup1.Key;

Answer 1

首先，让我们重命名示例查询的一些变量：

var queryNestedGroups =
    from e in source
    group e by e.Key1 into g1
    from e1 in
        (from e in g1
         group e by e.Key2)
    group e1 by g1.Key;

现在，您可以使用相同的模式添加另一个嵌套组级别：

var queryNestedGroups =
    from e in source
    group e by e.Key1 into g1
    from e1 in
        (from e in g1
         group e by e.Key2 into g2
         from e2 in 
            (from e in g2
             group e by e.Key3)
         group e2 by g2.Key)
    group e1 by g1.Key;

如何在linq中执行3个嵌套组

1 个答案: