这样就可以了:
Dim r1 As Row = Tables("办单信息").Current
Dim r2 As Row = Tables("办单信息").AddNew
For Each c As Col In Tables("办单信息").Cols
If c.name <> "PO号" Then
r2(c.name) = r1(c.name)
End If
Next
Dim val As String =DataTables("办单信息").Compute("Max(PO号)")
val = val.SubString(2)
r2("PO号") = "R-" & cint(val+1)
For Each dr1 As DataRow In r1.DataRow.GetChildRows("办单物料明细表")
Dim dr2 As DataRow = DataTables("办单物料明细表").AddNew()
For Each dc As DataCol In DataTables("办单物料明细表").DataCols
If dc.name <> "办单号" Then
dr2(dc.name) = dr1(dc.name)
End If
dr2("办单号") = r2("PO号")
Next
Next