Relationships between two xml

I'm creating a PDA app.
I'm using xml files as tables of a database.

When I select the CompanyName from a comboBox
I want the options in table2 that are equals to that CompanyName (using a ID to map)
to display in a second comboBox.

Can anyone help me because I have no clue how to do this.
This is how I get the xml in the comboBox :

//Set file names and create file streams
xmlFileName = "\\My Documents\\Company.xml";
xsdFileName = "\\My Documents\\Company.xsd";
FileStream FsXML = new FileStream(xmlFileName,FileMode.Open);
FileStream FsXSD = new FileStream(xsdFileName,FileMode.Open);
      XmlTextReader xtrXML = null;
      xtrXML = new XmlTextReader(FsXML);
      // Get a DataTable to conveniently use for binding.
      dt = companyDS.Tables["record"];
      //Bind the list box to state abreviations.
      comboBox1.DataSource = dt;
      comboBox1.DisplayMember = "CompanyName";
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sumixConnect With a Mentor Commented:

If you have the two tables in the dataset, i'll call them Companies and Employees for example, you can set a relation like this:
    CompaniesDS.Tables["Companies"].Columns["CompanyID"],       // column in parent table
    CompaniesDS.Tables["Employees"].Columns["CompanyID"]);      // column in child tablle

than, you can accomplish what you want very easy, by setting the DataSource and DisplayMember properties of the two combobxes this way:
comboBox1.DataSource = CompaniesDS.Tables["Companies"];
comboBox1.DisplayMember = "CompanyName";
comboBox2.DataSource = CompaniesDS.Tables["Companies"];  // the same data source - parent table !!!
comboBox2.DisplayMember = "MyRelation.EmployeeName";   // use here the relation name and the field in the child table !!!

btw, is there any reason for not reading the xml file in a simpler way, like:
    DataSet CompaniesDS = new DataSet();
    CompaniesDS.ReadXml("Company.xml");  ?

Gautham JanardhanCommented:
can u post the xml file what does it contain
Gautham JanardhanCommented:
and what is in ur dataset
Gautham JanardhanCommented:
if u have the second table in ur dataset then u dont have to establish any relation btw the xml

all u have to do is apply row filter to uur second table and apply that tables default view to the combobox as u have done
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