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我的任务是从填充在自联接表中的数据生成 XML 文件；所有 XML 文件都必须符合自联接中定义的层次结构。

我已经编写了一些递归代码来实现这一点并取得了一些成功，但我的逻辑似乎从未正确显示层次结构；某些父节点总是阻止显示为 ParentNodes 和作为子节点 - 没有后代。

例如，我有以下理想的 XML 结构：

 <?xml version="1.0" encoding="utf-8"?>  
 <MYREPORT>  
   <HEADER>  
    <HEADER_ID></HEADER_ID>  
    <HEADER_DESC></HEADER_DESC>  
    <HEADER_CODE></HEADER_CODE>  
    <HEADER_NAME></HEADER_NAME>  
    <HEADER_DATE></HEADER_DATE>  
    <HEADER_DATE2></HEADER_DATE2>  
    <AS_AT></AS_AT>  
  </HEADER>  
  <BODY>   
    <ITEMS_INFO>  
      <ITEM_CODE></ITEM_CODE>  
      <ITEM_DESC></ITEM_DESC>  
      <AMOUNT></AMOUNT>  
    </ITEMS_INFO>  
  </BODY>  
</MYREPORT>

从以下自联接表中提供数据（主键：ElementId，外键ParentId：）

ElementId   ElementName         ParentId    ElementLevel 
1           MYREPORT            NULL            0  
2       HEADER              1           1  
3       HEADER_ID           2           2  
4       HEADER_DESC         2           2  
5       HEADER_CODE         2           2  
6       HEADER_NAME         2           2  
7       HEADER_DATE         2           2  
8       HEADER _DATE2           2           2  
9       AS_AT               2           2  
10      BODY                1           1  
12      ITEMS_INFO          10          2  
13      ITEM_CODE           12          3  
14      ITEM_DESC           12          3  
15      AMOUNT              12          3

但是我继续获得以下 XML 输出，其中<ITEMS_INFO></ITEMS_INFO>显示为一个parentNode块（这是正确的），还有一个childNode- 没有后代（这是错误的）

<?xml version="1.0" encoding="utf-8"?>
<MYREPORT>
  <HEADER>
    <HEADER_ID>8:564</HEADER_ID>
    <HEADER_DESC>9:564</HEADER_DESC>
    <HEADER_CODE>10:564</HEADER_CODE>
    <HEADER_NAME>11:564</HEADER_NAME>
    <HEADER_DATE>12:564</HEADER_DATE>
    <HEADER_DATE2>13:564</HEADER_DATE2>
    <AS_AT>14:564</AS_AT>
 </HEADER>
 <BODY>
    <ITEMS_INFO>
      <ITEM_CODE>17:737</ITEM_CODE>
      <ITEM_DESC>18:737</ITEM_DESC>
      <AMOUNT>19:737</AMOUNT>
    </ITEMS_INFO>
    <ITEMS_INFO>20:737</ITEMS_INFO>
  </BODY>
</MYREPORT>

请查看我的递归代码是否存在任何逻辑漏洞以及如何最好地实现我理想的 XML 层次结构

Private xmlWriter As New XmlTextWriter(My.Settings.xmlPath & "Rep.xml", System.Text.Encoding.UTF8)
Sub Main()

    Try
        Dim ds As DataSet = SqlHelper.ExecuteDataset(My.Settings.SqlUserRoleServices, CommandType.StoredProcedure, "getTest")
        ds.Tables(1).Columns.Add("isParsed", GetType(System.Int16))
        ds.Tables(1).AcceptChanges()
        Dim dr As DataRelation = New DataRelation("ElementSelf", ds.Tables(1).Columns("ElementId"), ds.Tables(1).Columns("ParentId"), True)
        ds.Relations.Add(dr)

        xmlWriter.Formatting = Formatting.Indented
        For Each StartRow As DataRow In ds.Tables(0).Rows
            If StartRow.IsNull("ParentId") Then
                xmlWriter.WriteStartDocument()
                xmlWriter.WriteStartElement(StartRow("ElementName"))
            End If
        Next

        For Each parentRow As DataRow In ds.Tables(1).Rows
            If (Not parentRow.IsNull("ParentId")) And parentRow.IsNull("IsParsed") Then
                parentRow("IsParsed") = 1
                doRecursion(parentRow, dr, xmlWriter)
                parentRow.AcceptChanges()
            End If
        Next

        xmlWriter.WriteEndElement()
        xmlWriter.WriteEndDocument()
        xmlWriter.Flush()
        xmlWriter.Close()
    Catch ex As Exception
        Console.WriteLine(ex.Message)
        Console.ReadKey()
    End Try
End Sub

Private Sub doRecursion(ByRef parentRow As DataRow, ByRef dr As DataRelation, ByRef xmlwriter As XmlTextWriter)
    Dim children As DataRow() = parentRow.GetChildRows(dr)

    If children.Any Then
        xmlwriter.WriteStartElement(parentRow("ElementName").ToString)

        For Each brow As DataRow In children
            If brow("IsParsed") Is DBNull.Value Then
                brow("IsParsed") = 1
                brow.AcceptChanges()
                doRecursion(brow, dr, xmlwriter)
                xmlwriter.WriteElementString(brow("ElementName"), Date.Now.Second & ":" & Date.Now.Millisecond)
                System.Threading.Thread.Sleep(1000)
                brow.AcceptChanges()
                parentRow.AcceptChanges()
            Else
                Exit For
            End If
        Next
        xmlwriter.WriteEndElement()
    Else
        Return
    End If
End Sub

谢谢。

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