You have asked two different things in your two posts.

If you are talking about dependent listboxes that are automatically populated in sequense, getting the values from the database, the only way to do it is Ajax.
When you select a value in a listbox, all others under it are automatically set to have no values. When you select a value in this, the next is automatically populated with values that depend on the selected one. This is done using Javascript to capture the selected value, and a HTTPrequest object to send this value to a server side script (usually PHP, in some cases Perl) that will send back the response (which consists in the values that will populate the lower level listbox). Javasript is used as a last stage, to recieve these values and populate the second listbox, and so on.

For the treeview menus look where Terry suggested.

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