Hi everybody,

I have a tree view structure, which is stored in this table

select node_id, parent_id, root_id, descrip, sort_order  from ItemTree order by sort_order -- table has more fields, of course

Sort_Order is relevant to the parent_id.

I have the following procedure which is called every time the changes of any type are made to the tree view:

with thisform
	nChanges   = 0
	nSortOrder = 1
* Find a root node in the TreeView
	oTree = .TList2
	if oTree.Nodes.count > 0
		for i = 1 to oTree.Nodes.count
			oTmp = oTree.Nodes(i).parent
			if isnull(oTmp) then
				iTmpIndex = i
				exit
			endif
		next i
* Get the index of the root node that is at the top of the TreeView
		iIndex = oTree.Nodes(iTmpIndex).FirstSibling.index
		iTmpIndex = iIndex

		lnSeekVal = val(substr(oTree.Nodes(iIndex).key, 3))
		select itemtree
		set order to node_id
		seek lnSeekVal
		if node_id == lnSeekVal and lnSeekVal <> 0
			if thisform.nBaseRoot_id >= 0
				nSortOrder = sort_order
			else
				if sort_order <> nSortOrder
					replace sort_order with nSortOrder
					nChanges = nChanges + 1
					.lUpdateItemTree = .t.
				endif
			endif
		else
			.log("Seek Failed on node id:" + oTree.Nodes(iIndex).key, program(), 1)
		endif

* If the Node has Children call the sub that writes the children
		if oTree.Nodes(iIndex).Children > 0
			nChanges = nChanges + .SaveChild(iIndex)
		endif

		do while iIndex <> oTree.Nodes(iTmpIndex).LastSibling.index
*Loop through all the root nodes
			nSortOrder = nSortOrder + 1
			lnSeekVal  = val(substr(oTree.Nodes(iIndex).next.key, 3))
			select itemtree
			seek lnSeekVal
			if node_id == lnSeekVal and lnSeekVal <> 0
				if sort_order <> nSortOrder
					replace sort_order with nSortOrder
					nChanges = nChanges + 1
					.lUpdateItemTree = .t.
				endif
			else
				.log("Seek Failed on node id:" + oTree.Nodes(iIndex).next.key, program(), 1)
			endif
			if oTree.Nodes(iIndex).next.Children > 0
				nChange = nChanges + .SaveChild(oTree.Nodes(iIndex).next.index)
			endif
			iIndex = oTree.Nodes(iIndex).next.index
		enddo
	endif
	.log("Total number of changed records in the Item tree: " + alltrim(transform(m.nChanges,'@999,999,999')), program(), 1)
endwith

return nChanges

I found that even if I add a new item to the very bottom of one of the subtrees (and so I should not change more than 1 item), I still end up with the lots of changes.

I'm wondering if this algorithm can be improved to minimize number of changes written in the database?

Thanks a lot in advance for the suggestions.