how do sort the tree child

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C#

List<string> retList = new List<string>();
            FilterName.Clear();
            string connectionString = "Provider=Microsoft.JET.OLEDB.4.0;data source=" + strPath;
            OleDbConnection conn = new OleDbConnection(connectionString);
            string sql = "SELECT DISTINCT "+stringColName+" From " + strTable;
            OleDbCommand cmd = new OleDbCommand(sql, conn);
            conn.Open();
            OleDbDataReader reader;
            reader = cmd.ExecuteReader();
            TreeNode tn = null;

hello friends.
we use a database.i.e Provider=Microsoft.JET.OLEDB.4.0;
my application fetch the whole data from the database even tree node also..
i want to know how to do the sorting of tree child...

code is :

List<string> reeList = new List<string>();
            FilterName.Clear();
            string connectionString = "Provider=Microsoft.JET.OLEDB.4.0;data source=" + strPath;
            OleDbConnection conn = new OleDbConnection(connectionString);
            string sql = "SELECT DISTINCT "+stringColName+" From " + strTable;
            OleDbCommand cmd = new OleDbCommand(sql, conn);
            conn.Open();
            OleDbDataReader reader;
            reader = cmd.ExecuteReader();
            TreeNode tn = null; 
tn=new TreeNode(ParentNode);
while(reader.Read())
{
tn.Nodes>Add(reader.GetString(0),reader.GetString(0))
FilterName.Add(reader.GetString(0));
}</string></string>

please tell me how this code do the sort of tree child.