How to display null values in xml using dataset

I'm having an issue relating a xml document, i want to show null values ( they dont show up on xml structure ) as an empty string or something,

Example:

<?xml version="1.0" standalone="yes"?>
<SerialisedData>
  <xs:schema id="SerialisedData" xmlns="" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata" xmlns:msprop="urn:schemas-microsoft-com:xml-msprop">
    <xs:element name="SerialisedData" msdata:IsDataSet="true" msdata:UseCurrentLocale="true">
      <xs:complexType>
        <xs:choice minOccurs="0" maxOccurs="unbounded">
          <xs:element name="Table1" msprop:BaseTable.0="TABLE_NAME" msprop:BaseSchema="SCHEMA_NAME">
            <xs:complexType>
              <xs:sequence>
                <xs:element name="FILE" msprop:OraDbType="126" msprop:BaseColumn="FILE" type="xs:string" minOccurs="0" />
                <xs:element name="BBid" msprop:OraDbType="113" msprop:BaseColumn="BBid" type="xs:long" minOccurs="0" />
                <xs:element name="trnid" msprop:OraDbType="113" msprop:BaseColumn="trnid" type="xs:long" minOccurs="0" />
                <xs:element name="stnid" msprop:OraDbType="113" msprop:BaseColumn="stnid" type="xs:long" minOccurs="0" />
                <xs:element name="PIGGYBACK" msprop:OraDbType="126" msprop:BaseColumn="PIGGYBACK" type="xs:string" minOccurs="0" />
                <xs:element name="PAY_TYPE" msprop:OraDbType="126" msprop:BaseColumn="PAY_TYPE" type="xs:string" minOccurs="0" />
                <xs:element name="AMT" msprop:OraDbType="107" msprop:BaseColumn="AMT" type="xs:decimal" minOccurs="0" />
                <xs:element name="POSNUMBER" msprop:OraDbType="126" msprop:BaseColumn="POSNUMBER" type="xs:string" minOccurs="0" />
              </xs:sequence>
            </xs:complexType>
          </xs:element>
        </xs:choice>
      </xs:complexType>
    </xs:element>
  </xs:schema>

<Table1>
  <BBid>503101</BBid>
    <trnid>1377982613101</trnid>
    <stnid>13100</stnid>
    <PAY_TYPE>01</PAY_TYPE>
    <AMT>10000</AMT>
    <POSNUMBER>CCT001</POSNUMBER>
  </Table1>
  <Table1>
  <BBid>573101</BBid>
    <trnid>1377982723101</trnid>
    <stnid>13100</stnid>
    <PAY_TYPE>01</PAY_TYPE>
    <AMT>1000</AMT>
    <POSNUMBER>CCT001</POSNUMBER>
  </Table1>

I want to display like this (including the PIGGYBACK column):

<Table1>
 <BBid>573101</BBid>
    <trnid>1377982763101</trnid>
    <stnid>13100</stnid>
    <PAY_TYPE>01</PAY_TYPE>
    <AMT>9000</AMT>
    <POSNUMBER>CCT001</POSNUMBER>
    <PIGGYBACK></PIGGYBACK>
  </Table1>

<Table1>
 <BBid>573101</BBid>
    <trnid>1377982763101</trnid>
    <stnid>13100</stnid>
    <PAY_TYPE>01</PAY_TYPE>
    <AMT>9000</AMT>
    <POSNUMBER>CCT001</POSNUMBER>
    <PIGGYBACK></PIGGYBACK>
  </Table1>

My PIGGYBACK column contains/returns null from the view/table (DataSet) and I am referencing this column in my code further down.

I use the following to Write the XML file:

DataSet ds = new DataSet("SerialisedData");
        ds.WriteXml(@"C:\FileName.XML", XmlWriteMode.WriteSchema);

To Read the file:

DataSet ds = new DataSet("SerialisedData");
            ds.ReadXml(@"C:\FileName.XML", XmlReadMode.ReadSchema);

How can I do this?

Thank you in advance for your help.

Thanks!

Tags: C# 3.5