当然，您要执行

Sure, you're looking to perform a Full Outer Join on the data, which doesn't exist in LINQ, so we fake it with two unioned Left Outer Joins:

var A = from a in List1
    join b in List2 on new { a.Year, a.Month } equals new { b.Year, b.Month }
        into bgroup
    from b in bgroup.DefaultIfEmpty()
    select new { a.Year, a.Month, a.ValueA, ValueB = (b == null ? 0 : b.ValueB) };

var B = from b in List2
    join a in List1 on new { b.Year, b.Month } equals new { a.Year, a.Month } 
        into agroup
    from a in agroup.DefaultIfEmpty()
    select new { b.Year, b.Month, ValueA = (a == null ? 0 : a.ValueA), b.ValueB };

var List3 = A.Union(B);

为C#表示歉意，我无法使VB.Net示例在我的一生中都能正常工作.您需要将两个左外部联接合并以产生正确的答案.我尝试过的所有代码转换器都没有.

以下是LINQPad阻塞的VB.Net，但是我能找到的每个示例都应该是正确的:

The following is VB.Net that LINQPad chokes on, but every example I can find says should be correct:

Dim A = From a In List1 _
    Group Join b In List2 _
        On New With { a.Year, a.Month } Equals New With { b.Year, b.Month} _
        Into bGroup = Group _
    From b In bGroup.DefaultIfEmpty() _
    Select a.Year, a.Month, a.ValueA, ValueB = If(b Is Nothing, 0, b.ValueB)

Dim B = From b In List2 _
    Group Join a In List1 _
        On New With { b.Year, b.Month } Equals New With { a.Year, a.Month} _
        Into aGroup = Group _
    From a In aGroup.DefaultIfEmpty() _
    Select b.Year, b.Month, ValueA = If(a Is Nothing, 0, a.ValueA), b.ValueB

Dim List3 = A.Union(B)