How to create N Level Of TreeView from database in asp.net

NodeSpacing="0px" VerticalPadding="2px">

VerticalPadding="0px" />

 

CS-------- 

 

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Data;

using System.Data.SqlClient;

using System.Configuration;

public partial class N_level_Treeview : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

if (!this.IsPostBack)

{

DataTable dt = this.GetData("SELECT cId, cName FROM TopBill");

this.PopulateTreeView(dt, 0, null);

}

}

private void PopulateTreeView(DataTable dtParent, int parentId, TreeNode treeNode)

{

foreach (DataRow row in dtParent.Rows)

{

TreeNode child = new TreeNode

{

Text = row["cName"].ToString(),

Value = row["cId"].ToString()

};

if (parentId == 0)

{

TreeView1.Nodes.Add(child);

DataTable dtChild = this.GetData("SELECT srNo,cid, cName FROM TopBill WHERE pid = " + child.Value);

PopulateTreeView(dtChild, int.Parse(child.Value), child);

}

else

{

treeNode.ChildNodes.Add(child);

}

}

}

private DataTable GetData(string query)

{

DataTable dt = new DataTable();

string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;

using (SqlConnection con = new SqlConnection(constr))

{

using (SqlCommand cmd = new SqlCommand(query))

{

using (SqlDataAdapter sda = new SqlDataAdapter())

{

cmd.CommandType = CommandType.Text;

cmd.Connection = con;

sda.SelectCommand = cmd;

sda.Fill(dt);

}

}

return dt;

}

}

}

 

-------------- Current Output  of my Code is ....

 

 

 

 

In above picture , I am trying to show that if India has some child node, India Must me expandable so that i can see delhi,  If again Delhi Has some child Like Preet vihar , Laxmi Nagar, Delhi also must be expandable to see their child  and so on....

 

 

 

Please solve this issues..