Question

If I have this [Terminal] table:

ID bigint
Description varchar(20)
TerminalLevel smallint //1 = Terminal, 2 = Sub Terminal, 3 = Sub-sub-Terminal
TerminalID             //0 = Main Terminal itself, else belong to parent terminal

For example, I have:

ID           Description           TerminalLevel         TerminalID
1            Terminal 1            1                     0
2            Terminal 1-1          2                     1
3            Terminal 1-1-1        3                     2
4            Terminal 2            1                     0
5            Terminal 2-1          1                     4

I expect to load the data to the tree like this:

Terminal 1
  |---> Terminal 1-1
           |---> Terminal 1-1-1
Terminal 2
  |---> Terminal 2-1

Would it be possible to select only one query and load to a treeview in asp.net?

Answer 1

Get you query in a sqldatareader DReader but order by TerminalID to avoid child to be added before parent
and use the following functions

SqlDataReader DReader = load from databse order by TerminalID ...
TreeNode nodeNew;
    if (DReader.HasRows)
    while (DReader.Read())
        {
            nodeNew = new TreeNode(DReader["Description"].ToString(), DReader["ID"].ToString());
            if(DReader["TerminalID"].ToString() == "0")
                 treeview.Nodes.Add(nodeNew);
            else
             treeview.FindNode(DReader["TerminalLevel"].ToString().Replace("-","/")).ChildNodes.Add(nodeNew);

        }

UPDATE

if you are using sqldatareader you only need to order by terminalid and with advance of terminallevel you can use my solution, if you are using datatable or store data in a collection, you can use the solution of two functions to bind treeview one have parentNode of tree …

but here you have terminal level so you can search in node by path

My Regards