ASP.NET TreeView - Knowledge Base

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Populate the TreeView from a database query

Q:

How can I populate the TreeView from a database query?

A:

In ASP 

SQL = "SELECT * FROM myTable ORDER BY ParentId, ChildId"



Do Until Rs.EOF
oTree.Add Rs("ParentID"), Rs("ChildID"), TEXTorHTML
Rs.MoveNext
Loop


For ASP.NET

SQL = "SELECT * FROM myTable ORDER BY ParentId, ChildId"



Do While MyReader.Read()
oTree.Add(MyReader("ParentID"), MyReader("ChildID"), TEXTorHTML)
Loop

---
Important TIP 1: The only correct way to populate
any treeview from database is to use field Level_Index.
If you have column with some kind of tree deep Level Index, then your life will be very easy.
Just use query with ORDER BY Level_Index.
This way parents always will be populated before children.

Have a look over the "cs_Demo.aspx" / "vb_Demo.aspx" files from the oboutSuite / ASPTreeView folder.These samples contain treeviews populated from a database.
---

TIP 2: Try to set oTree.ShowLostRed = true
You will see children nodes added before their parents in red color.
This new property was added in dll version 2.0.14 and very useful for debugging.

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