code:

 
//create a dataset object
DataSet ds = new DataSet();
String sqlString = "Select descr, abbrev, orglvl, active, recid From dbo.organizationlist Order By 2";
String sqlString2 = "Select a.recid as deptid, a.descr as descr1, a.abbrev, a.orglvl, a.active ,b.[contact id] as cid ,rtrim(b.fname)  + ' ' +  IsNull(RTrim(b.mint),'') + ' ' + rtrim(b.sirname)  as Contact ,b.fname,isnull(mint,''),b.mint,b.sirname From dbo.organizationlist a join dbo.vw_Contacts_by_OrgList b On a.recid = b.[dept id] order by 3";
//create an dataadapter
SqlDataAdapter da = new SqlDataAdapter(sqlString.ToString(), sqlDS.ConnectionString.ToString());
//fill the dataset through the adapter
da.Fill(ds, "organizationlist");             
//create an dataadapter1
SqlDataAdapter da1 = new SqlDataAdapter(sqlString2.ToString(), sqlDS.ConnectionString.ToString());
//fill the dataset through the adapter
da1.Fill(ds, "contacts");
ds.Relations.Add("OrgToContacts",ds.Tables["organizationlist"].Columns["recid"], ds.Tables["contacts"].Columns["deptid"]);
//foreach loop(s)
foreach (DataRow dr in ds.Tables ["organizationlist"].Rows)                   
{
TreeNode tn = new TreeNode();
//DataRow dr = new DataRow();
//nodeSupp = new TreeNode(); 
//nodeSupp.Text = rowSupp("CompanyName"); 
tn.Text = dr["descr"].ToString();
tn.Value = dr["recid"].ToString();  //.ID = rowSupp("SupplierID"); 
//TreeView1.Nodes.Add(nodeSupp); 
this.TreeView5.Nodes.Add(tn);
foreach (DataRow cr in dr.GetChildRows("OrgToContacts"))                   //"contacts"].Rows)
{
   TreeNode cn = new TreeNode();
   cn.Text = cr["descr1"].ToString();
   cn.Value = cr["cid"].ToString();                 
   tn.ChildNodes.Add(cn);
}
}
//clean up
ds.Dispose();
da.Dispose();
da1.Dispose();
sqlDS.Dispose();