C#

SqlConnection con = new SqlConnection(Properties.Settings.Default.Database1ConnectionString);<br />
SqlCommand cmd = new SqlCommand();<br />
SqlDataAdapter adapter = new SqlDataAdapter();<br />
cmd.CommandText = "select * from t_books";<br />
cmd.Connection = con;<br />
adapter.SelectCommand = cmd;<br />
DataSet ds = new DataSet();<br />
<br />
SqlCommand cmd2 = new SqlCommand();<br />
SqlDataAdapter adapter2 = new SqlDataAdapter();<br />
cmd2.CommandText = "select * from t_sessions";<br />
cmd2.Connection = con;<br />
adapter2.SelectCommand = cmd2;<br />
<br />
adapter.Fill(ds, "t_books");<br />
adapter2.Fill(ds, "t_sessions");<br />
DataRelation dataRelation;<br />
DataColumn dc1 = ds.Tables["t_books"].Columns["bookID"];<br />
DataColumn dc2 = ds.Tables["t_sessions"].Columns["bookID"];<br />
dataRelation = new DataRelation("Relation1", dc1, dc2);<br />
ds.Relations.Add(dataRelation);<br />
<br />
TreeNode book;<br />
TreeNode session;<br />
<br />
foreach (DataRow row in ds.Tables["t_books"].Rows)<br />
            {<br />
                book = new TreeNode(string.Format("{0}", (string)row["bookName"]));<br />
                book.Tag = row;<br />
<br />
                ds.Tables["t_sessions"].DefaultView.RowFilter = "bookID="+ row["bookID"];<br />
                foreach (DataRow sessionRow in ds.Tables["t_sessions"].Rows)<br />
                {<br />
                    session = new TreeNode(string.Format("{0}", (int)sessionRow["bookID"]));<br />
                    session.Tag = sessionRow;                    <br />
                    book.Nodes.Add(session);<br />
                }<br />
                this.treeView1.Nodes.Add(book);<br />
            }

if (dateFrom.Value > dateTo.Value)
{
  Console.WriteLine(dateFrom.ToString());
  Console.WriteLine(dateTo.ToString());
  MessageBox.Show("Start date must me before end date", "Notice", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
  return;
}

XmlDocument xmlDoc = new XmlDocument();
xmlDoc.Load(sFile);

XmlElement elem = xmlDoc.CreateElement("card");

XmlAttribute attr = xmlDoc.CreateAttribute("number");
attr.Value = iCardNo.ToString();
elem.Attributes.Append(attr);

elem.InnerXml = "<front></front>";
XmlText textNode = xmlDoc.CreateTextNode(sCardFront);
elem.FirstChild.AppendChild(textNode);

elem.InnerXml = "<back></back>";
textNode = xmlDoc.CreateTextNode(sCardBack);
elem.LastChild.AppendChild(textNode);

xmlDoc.DocumentElement.AppendChild(elem);

xmlDoc.Save(sFile);