你给我看的东西看了，“禁止重复”本来就设为True了。看来不是这个问题。还

请再帮我看一下，谢谢了。
问题出在:r("凭证ID") = "合计"，应该怎么改？
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下面二个循环去掉任何一个都正常，二个都在就出错：a child row was

mutilple parents.

Dim dt1 As DataTable = DataTables("凭证")
Dim Customers As List(Of String)
Customers = dt1.GetUniqueValues("", "凭证类别")

With Tables("凭证明细")
For Each Customer As String In Customers
     Dim r As  Row = .Addnew()
     r("凭证ID") = "合计"
Next
End With

With Tables("凭证")
For Each Customer As String In Customers
     Dim r As  Row = .Addnew()
     r("凭证ID") = "合计"
Next
End With

凭证ID 列是用于关联的，你在这里赋值那么多行的“合计”不就重复了嘛，子表对应父表的关联是不能多对多的呀。

另外，你在父表或关联表上搞什么“合计”呢？？？