主题：关于XML的问题，初学，请发代码学习

代码没问题，我测试没问题。

只要你路径没写错，就不可能有问题。

你弹出msgbox(dzml2)、msgbox(f)的值看看

Dim db1 As WinForm.DropDownBox = e.Form.Controls("DropBox1")
Dim db2 As WinForm.DropDownBox = e.Form.Controls("DropBox2")
Dim dzml1 As String = db1.text
Dim dzml2 As String = db2.text
For Each f As String In FileSys.GetFiles(dzml2)
    If f.EndsWith(".xml") Then
        Dim txt As String = FileSys.ReadAllText(f, Encoding.utf8)
        Dim xmlDoc As New System.XML.XmlDocument
        xmlDoc.Loadxml(txt.Trim)
        Dim ndList  = xmlDoc.GetElementsByTagName("mxxx")
        For Each dr As object In ndlist
            Dim ndr As Row = Tables("表b").addnew
            For Each n As System.XML.XmlNode In dr.childNodes
                output.show(n.Name & " = " & n.InnerText)
                If n.name = "fpdm" Then
                    ndr("fa piao代码") = n.innertext
                End If
                If n.name = "fphm" Then
                    ndr("fa piao号码") = n.innertext
                End If
                If n.name = "gmfnsrsbh" Then
                    ndr("纳税人识别号") = n.innertext
                End If
                If n.name = "kprq" Then
                    Dim str = n.innertext
                    ndr("开piao日期") = str.SubString(0,4) + "-" + str.SubString(4,2) + "-" + str.SubString(6,2)
                End If
                If n.name = "je" Then
                    ndr("合计金额")  = n.innertext
                End If
                If n.name = "se" Then
                    ndr("合计税额") = n.innertext
                End If
                If n.name = "zfbz" Then
                    ndr("fa piao状态") = n.innertext
                End If
                ndr("价税合计") = val(ndr("合计税额"))+ val(ndr("合计金额"))
               
            Next
        Next
    End If
Next

这样是可以了，但是如何检查是否重复的数据行呢？使其不加载呢

这个

Dim ndr As Row = Tables("表b").addnew

改成

Dim ndr As dataRow = dataTables("表b").find("某列='" & dr("fpdm") & "'")

If ndr is Nothing then ndr = dataTables("表b").addnew

.NET Framework 版本：2.0.50727.8800
Foxtable 版本：2018.10.9.1
错误所在事件：窗口,窗口1,Button1,Click
详细错误信息：
没有为 字符串“fa piao代码 = '” 和 类型“XmlElement” 定义运算符“&”。

Dim db1 As WinForm.DropDownBox = e.Form.Controls("DropBox1")
Dim db2 As WinForm.DropDownBox = e.Form.Controls("DropBox2")
Dim dzml1 As String = db1.text
Dim dzml2 As String = db2.text
For Each f As String In FileSys.GetFiles(dzml2)
    If f.EndsWith(".xml") Then
        Dim txt As String = FileSys.ReadAllText(f, Encoding.utf8)
        Dim xmlDoc As New System.XML.XmlDocument
        xmlDoc.Loadxml(txt.Trim)
        Dim ndList  = xmlDoc.GetElementsByTagName("mxxx")
        For Each dr As object In ndlist
            Dim ndr As DataRow = DataTables("表b").find("fa piao代码 = '" & dr("fpdm") & "'And fa piao号码 = '" & dr("fphm") & "'")
            If ndr Is Nothing Then ndr = DataTables("表b").addnew
            For Each n As System.XML.XmlNode In dr.childNodes
                output.show(n.Name & " = " & n.InnerText)
                If n.name = "fpdm" Then
                    ndr("fa piao代码") = n.innertext
                End If
                If n.name = "fphm" Then
                    ndr("fa piao号码") = n.innertext
                End If
                If n.name = "gmfnsrsbh" Then
                    ndr("纳税人识别号") = n.innertext
                End If
                If n.name = "kprq" Then
                    Dim str = n.innertext
                    ndr("开piao日期") = str.SubString(0,4) + "-" + str.SubString(4,2) + "-" + str.SubString(6,2)
                End If
                If n.name = "je" Then
                    ndr("合计金额")  = n.innertext
                End If
                If n.name = "se" Then
                    ndr("合计税额") = n.innertext
                End If
                If n.name = "zfbz" Then
                    ndr("fa piao状态") = n.innertext
                End If
                ndr("价税合计") = val(ndr("合计税额"))+ val(ndr("合计金额"))
            Next
        Next
    End If
Next

怎么回事？

改成

Dim ndr As dataRow = dataTables("表b").find("某列='" & dr("fpdm").innertext & "'")

If ndr is Nothing then ndr = dataTables("表b").addnew

{客户编码}[分隔符]"~~"
// 每行格式 :
// 编码~~名称~~简码~~税号~~地址电话~~银行账号~~邮件地址~~备注~~身份证校验

请问这个表达式怎么不起作用？

Dim db3 As WinForm.DropDownBox = e.Form.Controls("DropBox3")
Dim dzml3 As String = db3.text
For Each f As String In FileSys.GetFiles(dzml3)
    If f.EndsWith(".txt") Then
        Dim txt As String = FileSys.ReadAllText(f, Encoding.Default)
        Dim mg As New Merger
        mg.SourcePath = dzml3
        mg.Format = "Delimited,~~"
        Dim Parts() As String = f.Split(".txt")
        Dim fo As String = Parts(0)
        Dim fs() As String = fo.Split("\")
        mg.SourceTableName =  fs(1) '指定要合并的表
        msgbox(fs(1))
        mg.DataTableName = "表c" '指定接收数据的表
        mg.Merge() '开始合并
    End If
Next