不能这样比较的。
Dim Arys As List(Of String()) = DataTables("明细").GetValues("月|材料") '列名用符号|分割
'注意循环变量是字符型数组,所以类型是String(),而不是String
For Each s As String() In DataTables("期初").GetValues("月|材料")
Dim contains As Boolean = False
For Each ary() As String In arys
If ary(0) = s(0) AndAlso ary(1) = s(1) Then
contains = True
Exit For
End If
Next
If contains = False Then
arys.add(s)
End If
Next