How can I add subchild nodes in treeview ? ASP.NET C#

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C#

ASP.NET

SQL-Server-2012

Hi..I have at tree view control which retrieve values from database .It retrieve database name according to userid.Here is my snapshot img
Here is my all database names.I want when i click on database name e.g UIIT then its comes blow(subchilds).Please tell me how can i do this.Here is my aspx.cs code :

What I have tried:

aspx.cs code :

public void getdata()
{
string user = Session["name"].ToString();
SqlConnection cnn = new SqlConnection("Data Source=HAMEED_KHAN\\SQLEXPRESS;Initial Catalog=db_compiler;Integrated Security=True");
        SqlCommand cmd2 = new SqlCommand("SELECT User_ID from tbl_user WHERE User_Name='" + user + "'", cnn);
        cnn.Open();
        string id = cmd2.ExecuteScalar().ToString();
        int ID = Int32.Parse(id);
        Session["UID"] = ID;
SqlCommand cmd = new SqlCommand("SELECT Database_Name FROM  Create_db WHERE User_ID='" + ID + "'", cnn);
SqlCommand cmd4 = new SqlCommand("SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_CATALOG='UIIT'", cnn);
        DataTable dt = new DataTable();
        DataTable dt2 = new DataTable();
        Master.FindControl("TreeView1");
        Master.FindControl("TreeView8");
        TreeView tv = (TreeView)Master.FindControl("TreeView1");
        TreeView tv8 = (TreeView)Master.FindControl("TreeView8");

        SqlDataAdapter da = new SqlDataAdapter(cmd);
        SqlDataAdapter da2 = new SqlDataAdapter(cmd4);
        da.Fill(dt);
        da2.Fill(dt2);
        cnn.Close();

        var parentNode = new TreeNode("Database");
        var parentNode2 = new TreeNode("Tables");
        if (dt.Rows.Count > 0)
{
  foreach (DataRow row in dt.Rows)
   {
    string value = row["Database_Name"] + "";
     parentNode.ChildNodes.Add(new TreeNode(value));
    parentNode2.ChildNodes.Add(new TreeNode(value));
    }
     foreach (DataRow row2 in dt2.Rows)
     {
      string value2 = row2["TABLE_NAME"] + "";
     parentNode.ChildNodes.Add(new TreeNode(value2));
    }


   // var temp = new TreeNode("More") { NavigateUrl = "~/More_DB.aspx" };
   // parentNode.ChildNodes.Add(temp);
   //  parentNode2.ChildNodes.Add(temp);
    }
       
    tv.Nodes.Add(parentNode);
   tv8.Nodes.Add(parentNode2);
  }

and here is my QUERY to retrieve table name from database,

SELECT TABLE_NAME
 FROM INFORMATION_SCHEMA.TABLES
 WHERE TABLE_CATALOG='UIIT'

Remember 'UIIT' is just sample.I retrieve table name of every database blow.Just in 'TABLES' column in pic.Thanks